--- /dev/null
+/*
+ * This driver implements I2C master functionality using the LSI API2C
+ * controller.
+ *
+ * NOTE: The controller has a limitation in that it can only do transfers of
+ * maximum 255 bytes at a time. If a larger transfer is attempted, error code
+ * (-EINVAL) is returned.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ */
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+
+#define SCL_WAIT_TIMEOUT_NS 25000000
+#define I2C_XFER_TIMEOUT (msecs_to_jiffies(250))
+#define I2C_STOP_TIMEOUT (msecs_to_jiffies(100))
+#define FIFO_SIZE 8
+
+#define GLOBAL_CONTROL 0x00
+#define GLOBAL_MST_EN BIT(0)
+#define GLOBAL_SLV_EN BIT(1)
+#define GLOBAL_IBML_EN BIT(2)
+#define INTERRUPT_STATUS 0x04
+#define INTERRUPT_ENABLE 0x08
+#define INT_SLV BIT(1)
+#define INT_MST BIT(0)
+#define WAIT_TIMER_CONTROL 0x0c
+#define WT_EN BIT(15)
+#define WT_VALUE(_x) ((_x) & 0x7fff)
+#define IBML_TIMEOUT 0x10
+#define IBML_LOW_MEXT 0x14
+#define IBML_LOW_SEXT 0x18
+#define TIMER_CLOCK_DIV 0x1c
+#define I2C_BUS_MONITOR 0x20
+#define SOFT_RESET 0x24
+#define MST_COMMAND 0x28
+#define CMD_BUSY (1<<3)
+#define CMD_MANUAL (0x00 | CMD_BUSY)
+#define CMD_AUTO (0x01 | CMD_BUSY)
+#define MST_RX_XFER 0x2c
+#define MST_TX_XFER 0x30
+#define MST_ADDR_1 0x34
+#define MST_ADDR_2 0x38
+#define MST_DATA 0x3c
+#define MST_TX_FIFO 0x40
+#define MST_RX_FIFO 0x44
+#define MST_INT_ENABLE 0x48
+#define MST_INT_STATUS 0x4c
+#define MST_STATUS_RFL (1 << 13) /* RX FIFO serivce */
+#define MST_STATUS_TFL (1 << 12) /* TX FIFO service */
+#define MST_STATUS_SNS (1 << 11) /* Manual mode done */
+#define MST_STATUS_SS (1 << 10) /* Automatic mode done */
+#define MST_STATUS_SCC (1 << 9) /* Stop complete */
+#define MST_STATUS_IP (1 << 8) /* Invalid parameter */
+#define MST_STATUS_TSS (1 << 7) /* Timeout */
+#define MST_STATUS_AL (1 << 6) /* Arbitration lost */
+#define MST_STATUS_ND (1 << 5) /* NAK on data phase */
+#define MST_STATUS_NA (1 << 4) /* NAK on address phase */
+#define MST_STATUS_NAK (MST_STATUS_NA | \
+ MST_STATUS_ND)
+#define MST_STATUS_ERR (MST_STATUS_NAK | \
+ MST_STATUS_AL | \
+ MST_STATUS_IP | \
+ MST_STATUS_TSS)
+#define MST_TX_BYTES_XFRD 0x50
+#define MST_RX_BYTES_XFRD 0x54
+#define SCL_HIGH_PERIOD 0x80
+#define SCL_LOW_PERIOD 0x84
+#define SPIKE_FLTR_LEN 0x88
+#define SDA_SETUP_TIME 0x8c
+#define SDA_HOLD_TIME 0x90
+
+/**
+ * axxia_i2c_dev - I2C device context
+ * @base: pointer to register struct
+ * @msg: pointer to current message
+ * @msg_xfrd: number of bytes transferred in msg
+ * @msg_err: error code for completed message
+ * @msg_complete: xfer completion object
+ * @dev: device reference
+ * @adapter: core i2c abstraction
+ * @i2c_clk: clock reference for i2c input clock
+ * @bus_clk_rate: current i2c bus clock rate
+ */
+struct axxia_i2c_dev {
+ void __iomem *base;
+ struct i2c_msg *msg;
+ size_t msg_xfrd;
+ int msg_err;
+ struct completion msg_complete;
+ struct device *dev;
+ struct i2c_adapter adapter;
+ struct clk *i2c_clk;
+ u32 bus_clk_rate;
+};
+
+static void i2c_int_disable(struct axxia_i2c_dev *idev, u32 mask)
+{
+ u32 int_en;
+
+ int_en = readl(idev->base + MST_INT_ENABLE);
+ writel(int_en & ~mask, idev->base + MST_INT_ENABLE);
+}
+
+static void i2c_int_enable(struct axxia_i2c_dev *idev, u32 mask)
+{
+ u32 int_en;
+
+ int_en = readl(idev->base + MST_INT_ENABLE);
+ writel(int_en | mask, idev->base + MST_INT_ENABLE);
+}
+
+/**
+ * ns_to_clk - Convert time (ns) to clock cycles for the given clock frequency.
+ */
+static u32 ns_to_clk(u64 ns, u32 clk_mhz)
+{
+ return div_u64(ns * clk_mhz, 1000);
+}
+
+static int axxia_i2c_init(struct axxia_i2c_dev *idev)
+{
+ u32 divisor = clk_get_rate(idev->i2c_clk) / idev->bus_clk_rate;
+ u32 clk_mhz = clk_get_rate(idev->i2c_clk) / 1000000;
+ u32 t_setup;
+ u32 t_high, t_low;
+ u32 tmo_clk;
+ u32 prescale;
+ unsigned long timeout;
+
+ dev_dbg(idev->dev, "rate=%uHz per_clk=%uMHz -> ratio=1:%u\n",
+ idev->bus_clk_rate, clk_mhz, divisor);
+
+ /* Reset controller */
+ writel(0x01, idev->base + SOFT_RESET);
+ timeout = jiffies + msecs_to_jiffies(100);
+ while (readl(idev->base + SOFT_RESET) & 1) {
+ if (time_after(jiffies, timeout)) {
+ dev_warn(idev->dev, "Soft reset failed\n");
+ break;
+ }
+ }
+
+ /* Enable Master Mode */
+ writel(0x1, idev->base + GLOBAL_CONTROL);
+
+ if (idev->bus_clk_rate <= 100000) {
+ /* Standard mode SCL 50/50, tSU:DAT = 250 ns */
+ t_high = divisor * 1 / 2;
+ t_low = divisor * 1 / 2;
+ t_setup = ns_to_clk(250, clk_mhz);
+ } else {
+ /* Fast mode SCL 33/66, tSU:DAT = 100 ns */
+ t_high = divisor * 1 / 3;
+ t_low = divisor * 2 / 3;
+ t_setup = ns_to_clk(100, clk_mhz);
+ }
+
+ /* SCL High Time */
+ writel(t_high, idev->base + SCL_HIGH_PERIOD);
+ /* SCL Low Time */
+ writel(t_low, idev->base + SCL_LOW_PERIOD);
+ /* SDA Setup Time */
+ writel(t_setup, idev->base + SDA_SETUP_TIME);
+ /* SDA Hold Time, 300ns */
+ writel(ns_to_clk(300, clk_mhz), idev->base + SDA_HOLD_TIME);
+ /* Filter <50ns spikes */
+ writel(ns_to_clk(50, clk_mhz), idev->base + SPIKE_FLTR_LEN);
+
+ /* Configure Time-Out Registers */
+ tmo_clk = ns_to_clk(SCL_WAIT_TIMEOUT_NS, clk_mhz);
+
+ /* Find prescaler value that makes tmo_clk fit in 15-bits counter. */
+ for (prescale = 0; prescale < 15; ++prescale) {
+ if (tmo_clk <= 0x7fff)
+ break;
+ tmo_clk >>= 1;
+ }
+ if (tmo_clk > 0x7fff)
+ tmo_clk = 0x7fff;
+
+ /* Prescale divider (log2) */
+ writel(prescale, idev->base + TIMER_CLOCK_DIV);
+ /* Timeout in divided clocks */
+ writel(WT_EN | WT_VALUE(tmo_clk), idev->base + WAIT_TIMER_CONTROL);
+
+ /* Mask all master interrupt bits */
+ i2c_int_disable(idev, ~0);
+
+ /* Interrupt enable */
+ writel(0x01, idev->base + INTERRUPT_ENABLE);
+
+ return 0;
+}
+
+static int i2c_m_rd(const struct i2c_msg *msg)
+{
+ return (msg->flags & I2C_M_RD) != 0;
+}
+
+static int i2c_m_ten(const struct i2c_msg *msg)
+{
+ return (msg->flags & I2C_M_TEN) != 0;
+}
+
+static int i2c_m_recv_len(const struct i2c_msg *msg)
+{
+ return (msg->flags & I2C_M_RECV_LEN) != 0;
+}
+
+/**
+ * axxia_i2c_empty_rx_fifo - Fetch data from RX FIFO and update SMBus block
+ * transfer length if this is the first byte of such a transfer.
+ */
+static int axxia_i2c_empty_rx_fifo(struct axxia_i2c_dev *idev)
+{
+ struct i2c_msg *msg = idev->msg;
+ size_t rx_fifo_avail = readl(idev->base + MST_RX_FIFO);
+ int bytes_to_transfer = min(rx_fifo_avail, msg->len - idev->msg_xfrd);
+
+ while (bytes_to_transfer-- > 0) {
+ int c = readl(idev->base + MST_DATA);
+
+ if (idev->msg_xfrd == 0 && i2c_m_recv_len(msg)) {
+ /*
+ * Check length byte for SMBus block read
+ */
+ if (c <= 0 || c > I2C_SMBUS_BLOCK_MAX) {
+ idev->msg_err = -EPROTO;
+ i2c_int_disable(idev, ~0);
+ complete(&idev->msg_complete);
+ break;
+ }
+ msg->len = 1 + c;
+ writel(msg->len, idev->base + MST_RX_XFER);
+ }
+ msg->buf[idev->msg_xfrd++] = c;
+ }
+
+ return 0;
+}
+
+/**
+ * axxia_i2c_fill_tx_fifo - Fill TX FIFO from current message buffer.
+ * @return: Number of bytes left to transfer.
+ */
+static int axxia_i2c_fill_tx_fifo(struct axxia_i2c_dev *idev)
+{
+ struct i2c_msg *msg = idev->msg;
+ size_t tx_fifo_avail = FIFO_SIZE - readl(idev->base + MST_TX_FIFO);
+ int bytes_to_transfer = min(tx_fifo_avail, msg->len - idev->msg_xfrd);
+ int ret = msg->len - idev->msg_xfrd - bytes_to_transfer;
+
+ while (bytes_to_transfer-- > 0)
+ writel(msg->buf[idev->msg_xfrd++], idev->base + MST_DATA);
+
+ return ret;
+}
+
+static irqreturn_t axxia_i2c_isr(int irq, void *_dev)
+{
+ struct axxia_i2c_dev *idev = _dev;
+ u32 status;
+
+ if (!(readl(idev->base + INTERRUPT_STATUS) & INT_MST))
+ return IRQ_NONE;
+
+ /* Read interrupt status bits */
+ status = readl(idev->base + MST_INT_STATUS);
+
+ if (!idev->msg) {
+ dev_warn(idev->dev, "unexpected interrupt\n");
+ goto out;
+ }
+
+ /* RX FIFO needs service? */
+ if (i2c_m_rd(idev->msg) && (status & MST_STATUS_RFL))
+ axxia_i2c_empty_rx_fifo(idev);
+
+ /* TX FIFO needs service? */
+ if (!i2c_m_rd(idev->msg) && (status & MST_STATUS_TFL)) {
+ if (axxia_i2c_fill_tx_fifo(idev) == 0)
+ i2c_int_disable(idev, MST_STATUS_TFL);
+ }
+
+ if (status & MST_STATUS_SCC) {
+ /* Stop completed */
+ i2c_int_disable(idev, ~0);
+ complete(&idev->msg_complete);
+ } else if (status & MST_STATUS_SNS) {
+ /* Transfer done */
+ i2c_int_disable(idev, ~0);
+ if (i2c_m_rd(idev->msg) && idev->msg_xfrd < idev->msg->len)
+ axxia_i2c_empty_rx_fifo(idev);
+ complete(&idev->msg_complete);
+ } else if (unlikely(status & MST_STATUS_ERR)) {
+ /* Transfer error */
+ i2c_int_disable(idev, ~0);
+ if (status & MST_STATUS_AL)
+ idev->msg_err = -EAGAIN;
+ else if (status & MST_STATUS_NAK)
+ idev->msg_err = -ENXIO;
+ else
+ idev->msg_err = -EIO;
+ dev_dbg(idev->dev, "error %#x, addr=%#x rx=%u/%u tx=%u/%u\n",
+ status,
+ idev->msg->addr,
+ readl(idev->base + MST_RX_BYTES_XFRD),
+ readl(idev->base + MST_RX_XFER),
+ readl(idev->base + MST_TX_BYTES_XFRD),
+ readl(idev->base + MST_TX_XFER));
+ complete(&idev->msg_complete);
+ }
+
+out:
+ /* Clear interrupt */
+ writel(INT_MST, idev->base + INTERRUPT_STATUS);
+
+ return IRQ_HANDLED;
+}
+
+static int axxia_i2c_xfer_msg(struct axxia_i2c_dev *idev, struct i2c_msg *msg)
+{
+ u32 int_mask = MST_STATUS_ERR | MST_STATUS_SNS;
+ u32 rx_xfer, tx_xfer;
+ u32 addr_1, addr_2;
+ int ret;
+
+ if (msg->len > 255) {
+ dev_warn(idev->dev, "unsupported length %u\n", msg->len);
+ return -EINVAL;
+ }
+
+ idev->msg = msg;
+ idev->msg_xfrd = 0;
+ idev->msg_err = 0;
+ reinit_completion(&idev->msg_complete);
+
+ if (i2c_m_ten(msg)) {
+ /* 10-bit address
+ * addr_1: 5'b11110 | addr[9:8] | (R/nW)
+ * addr_2: addr[7:0]
+ */
+ addr_1 = 0xF0 | ((msg->addr >> 7) & 0x06);
+ addr_2 = msg->addr & 0xFF;
+ } else {
+ /* 7-bit address
+ * addr_1: addr[6:0] | (R/nW)
+ * addr_2: dont care
+ */
+ addr_1 = (msg->addr << 1) & 0xFF;
+ addr_2 = 0;
+ }
+
+ if (i2c_m_rd(msg)) {
+ /* I2C read transfer */
+ rx_xfer = i2c_m_recv_len(msg) ? I2C_SMBUS_BLOCK_MAX : msg->len;
+ tx_xfer = 0;
+ addr_1 |= 1; /* Set the R/nW bit of the address */
+ } else {
+ /* I2C write transfer */
+ rx_xfer = 0;
+ tx_xfer = msg->len;
+ }
+
+ writel(rx_xfer, idev->base + MST_RX_XFER);
+ writel(tx_xfer, idev->base + MST_TX_XFER);
+ writel(addr_1, idev->base + MST_ADDR_1);
+ writel(addr_2, idev->base + MST_ADDR_2);
+
+ if (i2c_m_rd(msg))
+ int_mask |= MST_STATUS_RFL;
+ else if (axxia_i2c_fill_tx_fifo(idev) != 0)
+ int_mask |= MST_STATUS_TFL;
+
+ /* Start manual mode */
+ writel(CMD_MANUAL, idev->base + MST_COMMAND);
+
+ i2c_int_enable(idev, int_mask);
+
+ ret = wait_for_completion_timeout(&idev->msg_complete,
+ I2C_XFER_TIMEOUT);
+
+ i2c_int_disable(idev, int_mask);
+
+ if (readl(idev->base + MST_COMMAND) & CMD_BUSY)
+ dev_warn(idev->dev, "busy after xfer\n");
+
+ if (ret == 0)
+ idev->msg_err = -ETIMEDOUT;
+
+ if (unlikely(idev->msg_err) && idev->msg_err != -ENXIO)
+ axxia_i2c_init(idev);
+
+ return idev->msg_err;
+}
+
+static int axxia_i2c_stop(struct axxia_i2c_dev *idev)
+{
+ u32 int_mask = MST_STATUS_ERR | MST_STATUS_SCC;
+ int ret;
+
+ reinit_completion(&idev->msg_complete);
+
+ /* Issue stop */
+ writel(0xb, idev->base + MST_COMMAND);
+ i2c_int_enable(idev, int_mask);
+ ret = wait_for_completion_timeout(&idev->msg_complete,
+ I2C_STOP_TIMEOUT);
+ i2c_int_disable(idev, int_mask);
+ if (ret == 0)
+ return -ETIMEDOUT;
+
+ if (readl(idev->base + MST_COMMAND) & CMD_BUSY)
+ dev_warn(idev->dev, "busy after stop\n");
+
+ return 0;
+}
+
+static int
+axxia_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
+{
+ struct axxia_i2c_dev *idev = i2c_get_adapdata(adap);
+ int i;
+ int ret = 0;
+
+ for (i = 0; ret == 0 && i < num; ++i)
+ ret = axxia_i2c_xfer_msg(idev, &msgs[i]);
+
+ axxia_i2c_stop(idev);
+
+ return ret ? : i;
+}
+
+static u32 axxia_i2c_func(struct i2c_adapter *adap)
+{
+ u32 caps = (I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR |
+ I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA);
+ return caps;
+}
+
+static const struct i2c_algorithm axxia_i2c_algo = {
+ .master_xfer = axxia_i2c_xfer,
+ .functionality = axxia_i2c_func,
+};
+
+static int axxia_i2c_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct axxia_i2c_dev *idev = NULL;
+ struct resource *res;
+ void __iomem *base;
+ int irq;
+ int ret = 0;
+
+ idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL);
+ if (!idev)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0) {
+ dev_err(&pdev->dev, "missing interrupt resource\n");
+ return irq;
+ }
+
+ idev->i2c_clk = devm_clk_get(&pdev->dev, "i2c");
+ if (IS_ERR(idev->i2c_clk)) {
+ dev_err(&pdev->dev, "missing clock\n");
+ return PTR_ERR(idev->i2c_clk);
+ }
+
+ idev->base = base;
+ idev->dev = &pdev->dev;
+ init_completion(&idev->msg_complete);
+
+ of_property_read_u32(np, "clock-frequency", &idev->bus_clk_rate);
+ if (idev->bus_clk_rate == 0)
+ idev->bus_clk_rate = 100000; /* default clock rate */
+
+ ret = axxia_i2c_init(idev);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to initialize\n");
+ return ret;
+ }
+
+ ret = devm_request_irq(&pdev->dev, irq, axxia_i2c_isr, 0,
+ pdev->name, idev);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to claim IRQ%d\n", irq);
+ return ret;
+ }
+
+ clk_prepare_enable(idev->i2c_clk);
+
+ i2c_set_adapdata(&idev->adapter, idev);
+ strlcpy(idev->adapter.name, pdev->name, sizeof(idev->adapter.name));
+ idev->adapter.owner = THIS_MODULE;
+ idev->adapter.algo = &axxia_i2c_algo;
+ idev->adapter.dev.parent = &pdev->dev;
+ idev->adapter.dev.of_node = pdev->dev.of_node;
+
+ platform_set_drvdata(pdev, idev);
+
+ ret = i2c_add_adapter(&idev->adapter);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to add adapter\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static int axxia_i2c_remove(struct platform_device *pdev)
+{
+ struct axxia_i2c_dev *idev = platform_get_drvdata(pdev);
+
+ clk_disable_unprepare(idev->i2c_clk);
+ i2c_del_adapter(&idev->adapter);
+
+ return 0;
+}
+
+/* Match table for of_platform binding */
+static const struct of_device_id axxia_i2c_of_match[] = {
+ { .compatible = "lsi,api2c", },
+ {},
+};
+
+MODULE_DEVICE_TABLE(of, axxia_i2c_of_match);
+
+static struct platform_driver axxia_i2c_driver = {
+ .probe = axxia_i2c_probe,
+ .remove = axxia_i2c_remove,
+ .driver = {
+ .name = "axxia-i2c",
+ .of_match_table = axxia_i2c_of_match,
+ },
+};
+
+module_platform_driver(axxia_i2c_driver);
+
+MODULE_DESCRIPTION("Axxia I2C Bus driver");
+MODULE_AUTHOR("Anders Berg <anders.berg@lsi.com>");
+MODULE_LICENSE("GPL v2");
projects / GitHub / exynos8895 / android_kernel_samsung_universal8895.git / commitdiff