M: Guenter Roeck <guenter.roeck@ericsson.com>
L: linux-i2c@vger.kernel.org
S: Maintained
-F: drivers/i2c/muxes/pca9541.c
+F: drivers/i2c/muxes/i2c-mux-pca9541.c
PCA9564/PCA9665 I2C BUS DRIVER
M: Wolfram Sang <w.sang@pengutronix.de>
I2C Master Selector.
This driver can also be built as a module. If so, the module
- will be called pca9541.
+ will be called i2c-mux-pca9541.
config I2C_MUX_PCA954x
tristate "Philips PCA954x I2C Mux/switches"
I2C mux/switch devices.
This driver can also be built as a module. If so, the module
- will be called pca954x.
+ will be called i2c-mux-pca954x.
endmenu
# Makefile for multiplexer I2C chip drivers.
obj-$(CONFIG_I2C_MUX_GPIO) += gpio-i2cmux.o
-obj-$(CONFIG_I2C_MUX_PCA9541) += pca9541.o
-obj-$(CONFIG_I2C_MUX_PCA954x) += pca954x.o
+obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o
+obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o
ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
--- /dev/null
+/*
+ * I2C multiplexer driver for PCA9541 bus master selector
+ *
+ * Copyright (c) 2010 Ericsson AB.
+ *
+ * Author: Guenter Roeck <guenter.roeck@ericsson.com>
+ *
+ * Derived from:
+ * pca954x.c
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+
+#include <linux/i2c/pca954x.h>
+
+/*
+ * The PCA9541 is a bus master selector. It supports two I2C masters connected
+ * to a single slave bus.
+ *
+ * Before each bus transaction, a master has to acquire bus ownership. After the
+ * transaction is complete, bus ownership has to be released. This fits well
+ * into the I2C multiplexer framework, which provides select and release
+ * functions for this purpose. For this reason, this driver is modeled as
+ * single-channel I2C bus multiplexer.
+ *
+ * This driver assumes that the two bus masters are controlled by two different
+ * hosts. If a single host controls both masters, platform code has to ensure
+ * that only one of the masters is instantiated at any given time.
+ */
+
+#define PCA9541_CONTROL 0x01
+#define PCA9541_ISTAT 0x02
+
+#define PCA9541_CTL_MYBUS (1 << 0)
+#define PCA9541_CTL_NMYBUS (1 << 1)
+#define PCA9541_CTL_BUSON (1 << 2)
+#define PCA9541_CTL_NBUSON (1 << 3)
+#define PCA9541_CTL_BUSINIT (1 << 4)
+#define PCA9541_CTL_TESTON (1 << 6)
+#define PCA9541_CTL_NTESTON (1 << 7)
+
+#define PCA9541_ISTAT_INTIN (1 << 0)
+#define PCA9541_ISTAT_BUSINIT (1 << 1)
+#define PCA9541_ISTAT_BUSOK (1 << 2)
+#define PCA9541_ISTAT_BUSLOST (1 << 3)
+#define PCA9541_ISTAT_MYTEST (1 << 6)
+#define PCA9541_ISTAT_NMYTEST (1 << 7)
+
+#define BUSON (PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON)
+#define MYBUS (PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS)
+#define mybus(x) (!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)
+#define busoff(x) (!((x) & BUSON) || ((x) & BUSON) == BUSON)
+
+/* arbitration timeouts, in jiffies */
+#define ARB_TIMEOUT (HZ / 8) /* 125 ms until forcing bus ownership */
+#define ARB2_TIMEOUT (HZ / 4) /* 250 ms until acquisition failure */
+
+/* arbitration retry delays, in us */
+#define SELECT_DELAY_SHORT 50
+#define SELECT_DELAY_LONG 1000
+
+struct pca9541 {
+ struct i2c_adapter *mux_adap;
+ unsigned long select_timeout;
+ unsigned long arb_timeout;
+};
+
+static const struct i2c_device_id pca9541_id[] = {
+ {"pca9541", 0},
+ {}
+};
+
+MODULE_DEVICE_TABLE(i2c, pca9541_id);
+
+/*
+ * Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
+ * as they will try to lock the adapter a second time.
+ */
+static int pca9541_reg_write(struct i2c_client *client, u8 command, u8 val)
+{
+ struct i2c_adapter *adap = client->adapter;
+ int ret;
+
+ if (adap->algo->master_xfer) {
+ struct i2c_msg msg;
+ char buf[2];
+
+ msg.addr = client->addr;
+ msg.flags = 0;
+ msg.len = 2;
+ buf[0] = command;
+ buf[1] = val;
+ msg.buf = buf;
+ ret = adap->algo->master_xfer(adap, &msg, 1);
+ } else {
+ union i2c_smbus_data data;
+
+ data.byte = val;
+ ret = adap->algo->smbus_xfer(adap, client->addr,
+ client->flags,
+ I2C_SMBUS_WRITE,
+ command,
+ I2C_SMBUS_BYTE_DATA, &data);
+ }
+
+ return ret;
+}
+
+/*
+ * Read from chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
+ * as they will try to lock adapter a second time.
+ */
+static int pca9541_reg_read(struct i2c_client *client, u8 command)
+{
+ struct i2c_adapter *adap = client->adapter;
+ int ret;
+ u8 val;
+
+ if (adap->algo->master_xfer) {
+ struct i2c_msg msg[2] = {
+ {
+ .addr = client->addr,
+ .flags = 0,
+ .len = 1,
+ .buf = &command
+ },
+ {
+ .addr = client->addr,
+ .flags = I2C_M_RD,
+ .len = 1,
+ .buf = &val
+ }
+ };
+ ret = adap->algo->master_xfer(adap, msg, 2);
+ if (ret == 2)
+ ret = val;
+ else if (ret >= 0)
+ ret = -EIO;
+ } else {
+ union i2c_smbus_data data;
+
+ ret = adap->algo->smbus_xfer(adap, client->addr,
+ client->flags,
+ I2C_SMBUS_READ,
+ command,
+ I2C_SMBUS_BYTE_DATA, &data);
+ if (!ret)
+ ret = data.byte;
+ }
+ return ret;
+}
+
+/*
+ * Arbitration management functions
+ */
+
+/* Release bus. Also reset NTESTON and BUSINIT if it was set. */
+static void pca9541_release_bus(struct i2c_client *client)
+{
+ int reg;
+
+ reg = pca9541_reg_read(client, PCA9541_CONTROL);
+ if (reg >= 0 && !busoff(reg) && mybus(reg))
+ pca9541_reg_write(client, PCA9541_CONTROL,
+ (reg & PCA9541_CTL_NBUSON) >> 1);
+}
+
+/*
+ * Arbitration is defined as a two-step process. A bus master can only activate
+ * the slave bus if it owns it; otherwise it has to request ownership first.
+ * This multi-step process ensures that access contention is resolved
+ * gracefully.
+ *
+ * Bus Ownership Other master Action
+ * state requested access
+ * ----------------------------------------------------
+ * off - yes wait for arbitration timeout or
+ * for other master to drop request
+ * off no no take ownership
+ * off yes no turn on bus
+ * on yes - done
+ * on no - wait for arbitration timeout or
+ * for other master to release bus
+ *
+ * The main contention point occurs if the slave bus is off and both masters
+ * request ownership at the same time. In this case, one master will turn on
+ * the slave bus, believing that it owns it. The other master will request
+ * bus ownership. Result is that the bus is turned on, and master which did
+ * _not_ own the slave bus before ends up owning it.
+ */
+
+/* Control commands per PCA9541 datasheet */
+static const u8 pca9541_control[16] = {
+ 4, 0, 1, 5, 4, 4, 5, 5, 0, 0, 1, 1, 0, 4, 5, 1
+};
+
+/*
+ * Channel arbitration
+ *
+ * Return values:
+ * <0: error
+ * 0 : bus not acquired
+ * 1 : bus acquired
+ */
+static int pca9541_arbitrate(struct i2c_client *client)
+{
+ struct pca9541 *data = i2c_get_clientdata(client);
+ int reg;
+
+ reg = pca9541_reg_read(client, PCA9541_CONTROL);
+ if (reg < 0)
+ return reg;
+
+ if (busoff(reg)) {
+ int istat;
+ /*
+ * Bus is off. Request ownership or turn it on unless
+ * other master requested ownership.
+ */
+ istat = pca9541_reg_read(client, PCA9541_ISTAT);
+ if (!(istat & PCA9541_ISTAT_NMYTEST)
+ || time_is_before_eq_jiffies(data->arb_timeout)) {
+ /*
+ * Other master did not request ownership,
+ * or arbitration timeout expired. Take the bus.
+ */
+ pca9541_reg_write(client,
+ PCA9541_CONTROL,
+ pca9541_control[reg & 0x0f]
+ | PCA9541_CTL_NTESTON);
+ data->select_timeout = SELECT_DELAY_SHORT;
+ } else {
+ /*
+ * Other master requested ownership.
+ * Set extra long timeout to give it time to acquire it.
+ */
+ data->select_timeout = SELECT_DELAY_LONG * 2;
+ }
+ } else if (mybus(reg)) {
+ /*
+ * Bus is on, and we own it. We are done with acquisition.
+ * Reset NTESTON and BUSINIT, then return success.
+ */
+ if (reg & (PCA9541_CTL_NTESTON | PCA9541_CTL_BUSINIT))
+ pca9541_reg_write(client,
+ PCA9541_CONTROL,
+ reg & ~(PCA9541_CTL_NTESTON
+ | PCA9541_CTL_BUSINIT));
+ return 1;
+ } else {
+ /*
+ * Other master owns the bus.
+ * If arbitration timeout has expired, force ownership.
+ * Otherwise request it.
+ */
+ data->select_timeout = SELECT_DELAY_LONG;
+ if (time_is_before_eq_jiffies(data->arb_timeout)) {
+ /* Time is up, take the bus and reset it. */
+ pca9541_reg_write(client,
+ PCA9541_CONTROL,
+ pca9541_control[reg & 0x0f]
+ | PCA9541_CTL_BUSINIT
+ | PCA9541_CTL_NTESTON);
+ } else {
+ /* Request bus ownership if needed */
+ if (!(reg & PCA9541_CTL_NTESTON))
+ pca9541_reg_write(client,
+ PCA9541_CONTROL,
+ reg | PCA9541_CTL_NTESTON);
+ }
+ }
+ return 0;
+}
+
+static int pca9541_select_chan(struct i2c_adapter *adap, void *client, u32 chan)
+{
+ struct pca9541 *data = i2c_get_clientdata(client);
+ int ret;
+ unsigned long timeout = jiffies + ARB2_TIMEOUT;
+ /* give up after this time */
+
+ data->arb_timeout = jiffies + ARB_TIMEOUT;
+ /* force bus ownership after this time */
+
+ do {
+ ret = pca9541_arbitrate(client);
+ if (ret)
+ return ret < 0 ? ret : 0;
+
+ if (data->select_timeout == SELECT_DELAY_SHORT)
+ udelay(data->select_timeout);
+ else
+ msleep(data->select_timeout / 1000);
+ } while (time_is_after_eq_jiffies(timeout));
+
+ return -ETIMEDOUT;
+}
+
+static int pca9541_release_chan(struct i2c_adapter *adap,
+ void *client, u32 chan)
+{
+ pca9541_release_bus(client);
+ return 0;
+}
+
+/*
+ * I2C init/probing/exit functions
+ */
+static int pca9541_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct i2c_adapter *adap = client->adapter;
+ struct pca954x_platform_data *pdata = client->dev.platform_data;
+ struct pca9541 *data;
+ int force;
+ int ret = -ENODEV;
+
+ if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE_DATA))
+ goto err;
+
+ data = kzalloc(sizeof(struct pca9541), GFP_KERNEL);
+ if (!data) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ i2c_set_clientdata(client, data);
+
+ /*
+ * I2C accesses are unprotected here.
+ * We have to lock the adapter before releasing the bus.
+ */
+ i2c_lock_adapter(adap);
+ pca9541_release_bus(client);
+ i2c_unlock_adapter(adap);
+
+ /* Create mux adapter */
+
+ force = 0;
+ if (pdata)
+ force = pdata->modes[0].adap_id;
+ data->mux_adap = i2c_add_mux_adapter(adap, &client->dev, client,
+ force, 0,
+ pca9541_select_chan,
+ pca9541_release_chan);
+
+ if (data->mux_adap == NULL) {
+ dev_err(&client->dev, "failed to register master selector\n");
+ goto exit_free;
+ }
+
+ dev_info(&client->dev, "registered master selector for I2C %s\n",
+ client->name);
+
+ return 0;
+
+exit_free:
+ kfree(data);
+err:
+ return ret;
+}
+
+static int pca9541_remove(struct i2c_client *client)
+{
+ struct pca9541 *data = i2c_get_clientdata(client);
+
+ i2c_del_mux_adapter(data->mux_adap);
+
+ kfree(data);
+ return 0;
+}
+
+static struct i2c_driver pca9541_driver = {
+ .driver = {
+ .name = "pca9541",
+ .owner = THIS_MODULE,
+ },
+ .probe = pca9541_probe,
+ .remove = pca9541_remove,
+ .id_table = pca9541_id,
+};
+
+module_i2c_driver(pca9541_driver);
+
+MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
+MODULE_DESCRIPTION("PCA9541 I2C master selector driver");
+MODULE_LICENSE("GPL v2");
--- /dev/null
+/*
+ * I2C multiplexer
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
+ *
+ * This module supports the PCA954x series of I2C multiplexer/switch chips
+ * made by Philips Semiconductors.
+ * This includes the:
+ * PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
+ * and PCA9548.
+ *
+ * These chips are all controlled via the I2C bus itself, and all have a
+ * single 8-bit register. The upstream "parent" bus fans out to two,
+ * four, or eight downstream busses or channels; which of these
+ * are selected is determined by the chip type and register contents. A
+ * mux can select only one sub-bus at a time; a switch can select any
+ * combination simultaneously.
+ *
+ * Based on:
+ * pca954x.c from Kumar Gala <galak@kernel.crashing.org>
+ * Copyright (C) 2006
+ *
+ * Based on:
+ * pca954x.c from Ken Harrenstien
+ * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
+ *
+ * Based on:
+ * i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
+ * and
+ * pca9540.c from Jean Delvare <khali@linux-fr.org>.
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+
+#include <linux/i2c/pca954x.h>
+
+#define PCA954X_MAX_NCHANS 8
+
+enum pca_type {
+ pca_9540,
+ pca_9542,
+ pca_9543,
+ pca_9544,
+ pca_9545,
+ pca_9546,
+ pca_9547,
+ pca_9548,
+};
+
+struct pca954x {
+ enum pca_type type;
+ struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
+
+ u8 last_chan; /* last register value */
+};
+
+struct chip_desc {
+ u8 nchans;
+ u8 enable; /* used for muxes only */
+ enum muxtype {
+ pca954x_ismux = 0,
+ pca954x_isswi
+ } muxtype;
+};
+
+/* Provide specs for the PCA954x types we know about */
+static const struct chip_desc chips[] = {
+ [pca_9540] = {
+ .nchans = 2,
+ .enable = 0x4,
+ .muxtype = pca954x_ismux,
+ },
+ [pca_9543] = {
+ .nchans = 2,
+ .muxtype = pca954x_isswi,
+ },
+ [pca_9544] = {
+ .nchans = 4,
+ .enable = 0x4,
+ .muxtype = pca954x_ismux,
+ },
+ [pca_9545] = {
+ .nchans = 4,
+ .muxtype = pca954x_isswi,
+ },
+ [pca_9547] = {
+ .nchans = 8,
+ .enable = 0x8,
+ .muxtype = pca954x_ismux,
+ },
+ [pca_9548] = {
+ .nchans = 8,
+ .muxtype = pca954x_isswi,
+ },
+};
+
+static const struct i2c_device_id pca954x_id[] = {
+ { "pca9540", pca_9540 },
+ { "pca9542", pca_9540 },
+ { "pca9543", pca_9543 },
+ { "pca9544", pca_9544 },
+ { "pca9545", pca_9545 },
+ { "pca9546", pca_9545 },
+ { "pca9547", pca_9547 },
+ { "pca9548", pca_9548 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, pca954x_id);
+
+/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
+ for this as they will try to lock adapter a second time */
+static int pca954x_reg_write(struct i2c_adapter *adap,
+ struct i2c_client *client, u8 val)
+{
+ int ret = -ENODEV;
+
+ if (adap->algo->master_xfer) {
+ struct i2c_msg msg;
+ char buf[1];
+
+ msg.addr = client->addr;
+ msg.flags = 0;
+ msg.len = 1;
+ buf[0] = val;
+ msg.buf = buf;
+ ret = adap->algo->master_xfer(adap, &msg, 1);
+ } else {
+ union i2c_smbus_data data;
+ ret = adap->algo->smbus_xfer(adap, client->addr,
+ client->flags,
+ I2C_SMBUS_WRITE,
+ val, I2C_SMBUS_BYTE, &data);
+ }
+
+ return ret;
+}
+
+static int pca954x_select_chan(struct i2c_adapter *adap,
+ void *client, u32 chan)
+{
+ struct pca954x *data = i2c_get_clientdata(client);
+ const struct chip_desc *chip = &chips[data->type];
+ u8 regval;
+ int ret = 0;
+
+ /* we make switches look like muxes, not sure how to be smarter */
+ if (chip->muxtype == pca954x_ismux)
+ regval = chan | chip->enable;
+ else
+ regval = 1 << chan;
+
+ /* Only select the channel if its different from the last channel */
+ if (data->last_chan != regval) {
+ ret = pca954x_reg_write(adap, client, regval);
+ data->last_chan = regval;
+ }
+
+ return ret;
+}
+
+static int pca954x_deselect_mux(struct i2c_adapter *adap,
+ void *client, u32 chan)
+{
+ struct pca954x *data = i2c_get_clientdata(client);
+
+ /* Deselect active channel */
+ data->last_chan = 0;
+ return pca954x_reg_write(adap, client, data->last_chan);
+}
+
+/*
+ * I2C init/probing/exit functions
+ */
+static int pca954x_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
+ struct pca954x_platform_data *pdata = client->dev.platform_data;
+ int num, force;
+ struct pca954x *data;
+ int ret = -ENODEV;
+
+ if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
+ goto err;
+
+ data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
+ if (!data) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ i2c_set_clientdata(client, data);
+
+ /* Write the mux register at addr to verify
+ * that the mux is in fact present. This also
+ * initializes the mux to disconnected state.
+ */
+ if (i2c_smbus_write_byte(client, 0) < 0) {
+ dev_warn(&client->dev, "probe failed\n");
+ goto exit_free;
+ }
+
+ data->type = id->driver_data;
+ data->last_chan = 0; /* force the first selection */
+
+ /* Now create an adapter for each channel */
+ for (num = 0; num < chips[data->type].nchans; num++) {
+ force = 0; /* dynamic adap number */
+ if (pdata) {
+ if (num < pdata->num_modes)
+ /* force static number */
+ force = pdata->modes[num].adap_id;
+ else
+ /* discard unconfigured channels */
+ break;
+ }
+
+ data->virt_adaps[num] =
+ i2c_add_mux_adapter(adap, &client->dev, client,
+ force, num, pca954x_select_chan,
+ (pdata && pdata->modes[num].deselect_on_exit)
+ ? pca954x_deselect_mux : NULL);
+
+ if (data->virt_adaps[num] == NULL) {
+ ret = -ENODEV;
+ dev_err(&client->dev,
+ "failed to register multiplexed adapter"
+ " %d as bus %d\n", num, force);
+ goto virt_reg_failed;
+ }
+ }
+
+ dev_info(&client->dev,
+ "registered %d multiplexed busses for I2C %s %s\n",
+ num, chips[data->type].muxtype == pca954x_ismux
+ ? "mux" : "switch", client->name);
+
+ return 0;
+
+virt_reg_failed:
+ for (num--; num >= 0; num--)
+ i2c_del_mux_adapter(data->virt_adaps[num]);
+exit_free:
+ kfree(data);
+err:
+ return ret;
+}
+
+static int pca954x_remove(struct i2c_client *client)
+{
+ struct pca954x *data = i2c_get_clientdata(client);
+ const struct chip_desc *chip = &chips[data->type];
+ int i, err;
+
+ for (i = 0; i < chip->nchans; ++i)
+ if (data->virt_adaps[i]) {
+ err = i2c_del_mux_adapter(data->virt_adaps[i]);
+ if (err)
+ return err;
+ data->virt_adaps[i] = NULL;
+ }
+
+ kfree(data);
+ return 0;
+}
+
+static struct i2c_driver pca954x_driver = {
+ .driver = {
+ .name = "pca954x",
+ .owner = THIS_MODULE,
+ },
+ .probe = pca954x_probe,
+ .remove = pca954x_remove,
+ .id_table = pca954x_id,
+};
+
+module_i2c_driver(pca954x_driver);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
+MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
+MODULE_LICENSE("GPL v2");
+++ /dev/null
-/*
- * I2C multiplexer driver for PCA9541 bus master selector
- *
- * Copyright (c) 2010 Ericsson AB.
- *
- * Author: Guenter Roeck <guenter.roeck@ericsson.com>
- *
- * Derived from:
- * pca954x.c
- *
- * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
- * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
- *
- * This file is licensed under the terms of the GNU General Public
- * License version 2. This program is licensed "as is" without any
- * warranty of any kind, whether express or implied.
- */
-
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/jiffies.h>
-#include <linux/delay.h>
-#include <linux/slab.h>
-#include <linux/device.h>
-#include <linux/i2c.h>
-#include <linux/i2c-mux.h>
-
-#include <linux/i2c/pca954x.h>
-
-/*
- * The PCA9541 is a bus master selector. It supports two I2C masters connected
- * to a single slave bus.
- *
- * Before each bus transaction, a master has to acquire bus ownership. After the
- * transaction is complete, bus ownership has to be released. This fits well
- * into the I2C multiplexer framework, which provides select and release
- * functions for this purpose. For this reason, this driver is modeled as
- * single-channel I2C bus multiplexer.
- *
- * This driver assumes that the two bus masters are controlled by two different
- * hosts. If a single host controls both masters, platform code has to ensure
- * that only one of the masters is instantiated at any given time.
- */
-
-#define PCA9541_CONTROL 0x01
-#define PCA9541_ISTAT 0x02
-
-#define PCA9541_CTL_MYBUS (1 << 0)
-#define PCA9541_CTL_NMYBUS (1 << 1)
-#define PCA9541_CTL_BUSON (1 << 2)
-#define PCA9541_CTL_NBUSON (1 << 3)
-#define PCA9541_CTL_BUSINIT (1 << 4)
-#define PCA9541_CTL_TESTON (1 << 6)
-#define PCA9541_CTL_NTESTON (1 << 7)
-
-#define PCA9541_ISTAT_INTIN (1 << 0)
-#define PCA9541_ISTAT_BUSINIT (1 << 1)
-#define PCA9541_ISTAT_BUSOK (1 << 2)
-#define PCA9541_ISTAT_BUSLOST (1 << 3)
-#define PCA9541_ISTAT_MYTEST (1 << 6)
-#define PCA9541_ISTAT_NMYTEST (1 << 7)
-
-#define BUSON (PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON)
-#define MYBUS (PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS)
-#define mybus(x) (!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)
-#define busoff(x) (!((x) & BUSON) || ((x) & BUSON) == BUSON)
-
-/* arbitration timeouts, in jiffies */
-#define ARB_TIMEOUT (HZ / 8) /* 125 ms until forcing bus ownership */
-#define ARB2_TIMEOUT (HZ / 4) /* 250 ms until acquisition failure */
-
-/* arbitration retry delays, in us */
-#define SELECT_DELAY_SHORT 50
-#define SELECT_DELAY_LONG 1000
-
-struct pca9541 {
- struct i2c_adapter *mux_adap;
- unsigned long select_timeout;
- unsigned long arb_timeout;
-};
-
-static const struct i2c_device_id pca9541_id[] = {
- {"pca9541", 0},
- {}
-};
-
-MODULE_DEVICE_TABLE(i2c, pca9541_id);
-
-/*
- * Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
- * as they will try to lock the adapter a second time.
- */
-static int pca9541_reg_write(struct i2c_client *client, u8 command, u8 val)
-{
- struct i2c_adapter *adap = client->adapter;
- int ret;
-
- if (adap->algo->master_xfer) {
- struct i2c_msg msg;
- char buf[2];
-
- msg.addr = client->addr;
- msg.flags = 0;
- msg.len = 2;
- buf[0] = command;
- buf[1] = val;
- msg.buf = buf;
- ret = adap->algo->master_xfer(adap, &msg, 1);
- } else {
- union i2c_smbus_data data;
-
- data.byte = val;
- ret = adap->algo->smbus_xfer(adap, client->addr,
- client->flags,
- I2C_SMBUS_WRITE,
- command,
- I2C_SMBUS_BYTE_DATA, &data);
- }
-
- return ret;
-}
-
-/*
- * Read from chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
- * as they will try to lock adapter a second time.
- */
-static int pca9541_reg_read(struct i2c_client *client, u8 command)
-{
- struct i2c_adapter *adap = client->adapter;
- int ret;
- u8 val;
-
- if (adap->algo->master_xfer) {
- struct i2c_msg msg[2] = {
- {
- .addr = client->addr,
- .flags = 0,
- .len = 1,
- .buf = &command
- },
- {
- .addr = client->addr,
- .flags = I2C_M_RD,
- .len = 1,
- .buf = &val
- }
- };
- ret = adap->algo->master_xfer(adap, msg, 2);
- if (ret == 2)
- ret = val;
- else if (ret >= 0)
- ret = -EIO;
- } else {
- union i2c_smbus_data data;
-
- ret = adap->algo->smbus_xfer(adap, client->addr,
- client->flags,
- I2C_SMBUS_READ,
- command,
- I2C_SMBUS_BYTE_DATA, &data);
- if (!ret)
- ret = data.byte;
- }
- return ret;
-}
-
-/*
- * Arbitration management functions
- */
-
-/* Release bus. Also reset NTESTON and BUSINIT if it was set. */
-static void pca9541_release_bus(struct i2c_client *client)
-{
- int reg;
-
- reg = pca9541_reg_read(client, PCA9541_CONTROL);
- if (reg >= 0 && !busoff(reg) && mybus(reg))
- pca9541_reg_write(client, PCA9541_CONTROL,
- (reg & PCA9541_CTL_NBUSON) >> 1);
-}
-
-/*
- * Arbitration is defined as a two-step process. A bus master can only activate
- * the slave bus if it owns it; otherwise it has to request ownership first.
- * This multi-step process ensures that access contention is resolved
- * gracefully.
- *
- * Bus Ownership Other master Action
- * state requested access
- * ----------------------------------------------------
- * off - yes wait for arbitration timeout or
- * for other master to drop request
- * off no no take ownership
- * off yes no turn on bus
- * on yes - done
- * on no - wait for arbitration timeout or
- * for other master to release bus
- *
- * The main contention point occurs if the slave bus is off and both masters
- * request ownership at the same time. In this case, one master will turn on
- * the slave bus, believing that it owns it. The other master will request
- * bus ownership. Result is that the bus is turned on, and master which did
- * _not_ own the slave bus before ends up owning it.
- */
-
-/* Control commands per PCA9541 datasheet */
-static const u8 pca9541_control[16] = {
- 4, 0, 1, 5, 4, 4, 5, 5, 0, 0, 1, 1, 0, 4, 5, 1
-};
-
-/*
- * Channel arbitration
- *
- * Return values:
- * <0: error
- * 0 : bus not acquired
- * 1 : bus acquired
- */
-static int pca9541_arbitrate(struct i2c_client *client)
-{
- struct pca9541 *data = i2c_get_clientdata(client);
- int reg;
-
- reg = pca9541_reg_read(client, PCA9541_CONTROL);
- if (reg < 0)
- return reg;
-
- if (busoff(reg)) {
- int istat;
- /*
- * Bus is off. Request ownership or turn it on unless
- * other master requested ownership.
- */
- istat = pca9541_reg_read(client, PCA9541_ISTAT);
- if (!(istat & PCA9541_ISTAT_NMYTEST)
- || time_is_before_eq_jiffies(data->arb_timeout)) {
- /*
- * Other master did not request ownership,
- * or arbitration timeout expired. Take the bus.
- */
- pca9541_reg_write(client,
- PCA9541_CONTROL,
- pca9541_control[reg & 0x0f]
- | PCA9541_CTL_NTESTON);
- data->select_timeout = SELECT_DELAY_SHORT;
- } else {
- /*
- * Other master requested ownership.
- * Set extra long timeout to give it time to acquire it.
- */
- data->select_timeout = SELECT_DELAY_LONG * 2;
- }
- } else if (mybus(reg)) {
- /*
- * Bus is on, and we own it. We are done with acquisition.
- * Reset NTESTON and BUSINIT, then return success.
- */
- if (reg & (PCA9541_CTL_NTESTON | PCA9541_CTL_BUSINIT))
- pca9541_reg_write(client,
- PCA9541_CONTROL,
- reg & ~(PCA9541_CTL_NTESTON
- | PCA9541_CTL_BUSINIT));
- return 1;
- } else {
- /*
- * Other master owns the bus.
- * If arbitration timeout has expired, force ownership.
- * Otherwise request it.
- */
- data->select_timeout = SELECT_DELAY_LONG;
- if (time_is_before_eq_jiffies(data->arb_timeout)) {
- /* Time is up, take the bus and reset it. */
- pca9541_reg_write(client,
- PCA9541_CONTROL,
- pca9541_control[reg & 0x0f]
- | PCA9541_CTL_BUSINIT
- | PCA9541_CTL_NTESTON);
- } else {
- /* Request bus ownership if needed */
- if (!(reg & PCA9541_CTL_NTESTON))
- pca9541_reg_write(client,
- PCA9541_CONTROL,
- reg | PCA9541_CTL_NTESTON);
- }
- }
- return 0;
-}
-
-static int pca9541_select_chan(struct i2c_adapter *adap, void *client, u32 chan)
-{
- struct pca9541 *data = i2c_get_clientdata(client);
- int ret;
- unsigned long timeout = jiffies + ARB2_TIMEOUT;
- /* give up after this time */
-
- data->arb_timeout = jiffies + ARB_TIMEOUT;
- /* force bus ownership after this time */
-
- do {
- ret = pca9541_arbitrate(client);
- if (ret)
- return ret < 0 ? ret : 0;
-
- if (data->select_timeout == SELECT_DELAY_SHORT)
- udelay(data->select_timeout);
- else
- msleep(data->select_timeout / 1000);
- } while (time_is_after_eq_jiffies(timeout));
-
- return -ETIMEDOUT;
-}
-
-static int pca9541_release_chan(struct i2c_adapter *adap,
- void *client, u32 chan)
-{
- pca9541_release_bus(client);
- return 0;
-}
-
-/*
- * I2C init/probing/exit functions
- */
-static int pca9541_probe(struct i2c_client *client,
- const struct i2c_device_id *id)
-{
- struct i2c_adapter *adap = client->adapter;
- struct pca954x_platform_data *pdata = client->dev.platform_data;
- struct pca9541 *data;
- int force;
- int ret = -ENODEV;
-
- if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE_DATA))
- goto err;
-
- data = kzalloc(sizeof(struct pca9541), GFP_KERNEL);
- if (!data) {
- ret = -ENOMEM;
- goto err;
- }
-
- i2c_set_clientdata(client, data);
-
- /*
- * I2C accesses are unprotected here.
- * We have to lock the adapter before releasing the bus.
- */
- i2c_lock_adapter(adap);
- pca9541_release_bus(client);
- i2c_unlock_adapter(adap);
-
- /* Create mux adapter */
-
- force = 0;
- if (pdata)
- force = pdata->modes[0].adap_id;
- data->mux_adap = i2c_add_mux_adapter(adap, &client->dev, client,
- force, 0,
- pca9541_select_chan,
- pca9541_release_chan);
-
- if (data->mux_adap == NULL) {
- dev_err(&client->dev, "failed to register master selector\n");
- goto exit_free;
- }
-
- dev_info(&client->dev, "registered master selector for I2C %s\n",
- client->name);
-
- return 0;
-
-exit_free:
- kfree(data);
-err:
- return ret;
-}
-
-static int pca9541_remove(struct i2c_client *client)
-{
- struct pca9541 *data = i2c_get_clientdata(client);
-
- i2c_del_mux_adapter(data->mux_adap);
-
- kfree(data);
- return 0;
-}
-
-static struct i2c_driver pca9541_driver = {
- .driver = {
- .name = "pca9541",
- .owner = THIS_MODULE,
- },
- .probe = pca9541_probe,
- .remove = pca9541_remove,
- .id_table = pca9541_id,
-};
-
-module_i2c_driver(pca9541_driver);
-
-MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
-MODULE_DESCRIPTION("PCA9541 I2C master selector driver");
-MODULE_LICENSE("GPL v2");
+++ /dev/null
-/*
- * I2C multiplexer
- *
- * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
- * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
- *
- * This module supports the PCA954x series of I2C multiplexer/switch chips
- * made by Philips Semiconductors.
- * This includes the:
- * PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
- * and PCA9548.
- *
- * These chips are all controlled via the I2C bus itself, and all have a
- * single 8-bit register. The upstream "parent" bus fans out to two,
- * four, or eight downstream busses or channels; which of these
- * are selected is determined by the chip type and register contents. A
- * mux can select only one sub-bus at a time; a switch can select any
- * combination simultaneously.
- *
- * Based on:
- * pca954x.c from Kumar Gala <galak@kernel.crashing.org>
- * Copyright (C) 2006
- *
- * Based on:
- * pca954x.c from Ken Harrenstien
- * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
- *
- * Based on:
- * i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
- * and
- * pca9540.c from Jean Delvare <khali@linux-fr.org>.
- *
- * This file is licensed under the terms of the GNU General Public
- * License version 2. This program is licensed "as is" without any
- * warranty of any kind, whether express or implied.
- */
-
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/slab.h>
-#include <linux/device.h>
-#include <linux/i2c.h>
-#include <linux/i2c-mux.h>
-
-#include <linux/i2c/pca954x.h>
-
-#define PCA954X_MAX_NCHANS 8
-
-enum pca_type {
- pca_9540,
- pca_9542,
- pca_9543,
- pca_9544,
- pca_9545,
- pca_9546,
- pca_9547,
- pca_9548,
-};
-
-struct pca954x {
- enum pca_type type;
- struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
-
- u8 last_chan; /* last register value */
-};
-
-struct chip_desc {
- u8 nchans;
- u8 enable; /* used for muxes only */
- enum muxtype {
- pca954x_ismux = 0,
- pca954x_isswi
- } muxtype;
-};
-
-/* Provide specs for the PCA954x types we know about */
-static const struct chip_desc chips[] = {
- [pca_9540] = {
- .nchans = 2,
- .enable = 0x4,
- .muxtype = pca954x_ismux,
- },
- [pca_9543] = {
- .nchans = 2,
- .muxtype = pca954x_isswi,
- },
- [pca_9544] = {
- .nchans = 4,
- .enable = 0x4,
- .muxtype = pca954x_ismux,
- },
- [pca_9545] = {
- .nchans = 4,
- .muxtype = pca954x_isswi,
- },
- [pca_9547] = {
- .nchans = 8,
- .enable = 0x8,
- .muxtype = pca954x_ismux,
- },
- [pca_9548] = {
- .nchans = 8,
- .muxtype = pca954x_isswi,
- },
-};
-
-static const struct i2c_device_id pca954x_id[] = {
- { "pca9540", pca_9540 },
- { "pca9542", pca_9540 },
- { "pca9543", pca_9543 },
- { "pca9544", pca_9544 },
- { "pca9545", pca_9545 },
- { "pca9546", pca_9545 },
- { "pca9547", pca_9547 },
- { "pca9548", pca_9548 },
- { }
-};
-MODULE_DEVICE_TABLE(i2c, pca954x_id);
-
-/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
- for this as they will try to lock adapter a second time */
-static int pca954x_reg_write(struct i2c_adapter *adap,
- struct i2c_client *client, u8 val)
-{
- int ret = -ENODEV;
-
- if (adap->algo->master_xfer) {
- struct i2c_msg msg;
- char buf[1];
-
- msg.addr = client->addr;
- msg.flags = 0;
- msg.len = 1;
- buf[0] = val;
- msg.buf = buf;
- ret = adap->algo->master_xfer(adap, &msg, 1);
- } else {
- union i2c_smbus_data data;
- ret = adap->algo->smbus_xfer(adap, client->addr,
- client->flags,
- I2C_SMBUS_WRITE,
- val, I2C_SMBUS_BYTE, &data);
- }
-
- return ret;
-}
-
-static int pca954x_select_chan(struct i2c_adapter *adap,
- void *client, u32 chan)
-{
- struct pca954x *data = i2c_get_clientdata(client);
- const struct chip_desc *chip = &chips[data->type];
- u8 regval;
- int ret = 0;
-
- /* we make switches look like muxes, not sure how to be smarter */
- if (chip->muxtype == pca954x_ismux)
- regval = chan | chip->enable;
- else
- regval = 1 << chan;
-
- /* Only select the channel if its different from the last channel */
- if (data->last_chan != regval) {
- ret = pca954x_reg_write(adap, client, regval);
- data->last_chan = regval;
- }
-
- return ret;
-}
-
-static int pca954x_deselect_mux(struct i2c_adapter *adap,
- void *client, u32 chan)
-{
- struct pca954x *data = i2c_get_clientdata(client);
-
- /* Deselect active channel */
- data->last_chan = 0;
- return pca954x_reg_write(adap, client, data->last_chan);
-}
-
-/*
- * I2C init/probing/exit functions
- */
-static int pca954x_probe(struct i2c_client *client,
- const struct i2c_device_id *id)
-{
- struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
- struct pca954x_platform_data *pdata = client->dev.platform_data;
- int num, force;
- struct pca954x *data;
- int ret = -ENODEV;
-
- if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
- goto err;
-
- data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
- if (!data) {
- ret = -ENOMEM;
- goto err;
- }
-
- i2c_set_clientdata(client, data);
-
- /* Write the mux register at addr to verify
- * that the mux is in fact present. This also
- * initializes the mux to disconnected state.
- */
- if (i2c_smbus_write_byte(client, 0) < 0) {
- dev_warn(&client->dev, "probe failed\n");
- goto exit_free;
- }
-
- data->type = id->driver_data;
- data->last_chan = 0; /* force the first selection */
-
- /* Now create an adapter for each channel */
- for (num = 0; num < chips[data->type].nchans; num++) {
- force = 0; /* dynamic adap number */
- if (pdata) {
- if (num < pdata->num_modes)
- /* force static number */
- force = pdata->modes[num].adap_id;
- else
- /* discard unconfigured channels */
- break;
- }
-
- data->virt_adaps[num] =
- i2c_add_mux_adapter(adap, &client->dev, client,
- force, num, pca954x_select_chan,
- (pdata && pdata->modes[num].deselect_on_exit)
- ? pca954x_deselect_mux : NULL);
-
- if (data->virt_adaps[num] == NULL) {
- ret = -ENODEV;
- dev_err(&client->dev,
- "failed to register multiplexed adapter"
- " %d as bus %d\n", num, force);
- goto virt_reg_failed;
- }
- }
-
- dev_info(&client->dev,
- "registered %d multiplexed busses for I2C %s %s\n",
- num, chips[data->type].muxtype == pca954x_ismux
- ? "mux" : "switch", client->name);
-
- return 0;
-
-virt_reg_failed:
- for (num--; num >= 0; num--)
- i2c_del_mux_adapter(data->virt_adaps[num]);
-exit_free:
- kfree(data);
-err:
- return ret;
-}
-
-static int pca954x_remove(struct i2c_client *client)
-{
- struct pca954x *data = i2c_get_clientdata(client);
- const struct chip_desc *chip = &chips[data->type];
- int i, err;
-
- for (i = 0; i < chip->nchans; ++i)
- if (data->virt_adaps[i]) {
- err = i2c_del_mux_adapter(data->virt_adaps[i]);
- if (err)
- return err;
- data->virt_adaps[i] = NULL;
- }
-
- kfree(data);
- return 0;
-}
-
-static struct i2c_driver pca954x_driver = {
- .driver = {
- .name = "pca954x",
- .owner = THIS_MODULE,
- },
- .probe = pca954x_probe,
- .remove = pca954x_remove,
- .id_table = pca954x_id,
-};
-
-module_i2c_driver(pca954x_driver);
-
-MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
-MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
-MODULE_LICENSE("GPL v2");
projects / GitHub / mt8127 / android_kernel_alcatel_ttab.git / commitdiff