leds: Add support for Philips PCA955x I2C LED drivers
authorNate Case <ncase@xes-inc.com>
Wed, 16 Jul 2008 21:49:55 +0000 (22:49 +0100)
committerRichard Purdie <rpurdie@rpsys.net>
Wed, 23 Jul 2008 08:49:56 +0000 (09:49 +0100)
This driver supports the PCA9550, PCA9551, PCA9552, and PCA9553
LED driver chips.

Signed-off-by: Nate Case <ncase@xes-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
drivers/leds/Kconfig
drivers/leds/Makefile
drivers/leds/leds-pca955x.c [new file with mode: 0644]
include/linux/leds.h

index 1c35dfaef721223505a5b5899647d4565f67e5ed..9556262dda5aabba7b6474eee2b4e2a3b1a31906 100644 (file)
@@ -155,6 +155,14 @@ config LEDS_CLEVO_MAIL
          To compile this driver as a module, choose M here: the
          module will be called leds-clevo-mail.
 
+config LEDS_PCA955X
+       tristate "LED Support for PCA955x I2C chips"
+       depends on LEDS_CLASS && I2C
+       help
+         This option enables support for LEDs connected to PCA955x
+         LED driver chips accessed via the I2C bus.  Supported
+         devices include PCA9550, PCA9551, PCA9552, and PCA9553.
+
 comment "LED Triggers"
 
 config LEDS_TRIGGERS
index 7156f9970fa93edcade9fb3592a5364e071ab7f1..ff7982b44565d7fe674b0846916a8acb2d221666 100644 (file)
@@ -22,6 +22,7 @@ obj-$(CONFIG_LEDS_CM_X270)              += leds-cm-x270.o
 obj-$(CONFIG_LEDS_CLEVO_MAIL)          += leds-clevo-mail.o
 obj-$(CONFIG_LEDS_HP6XX)               += leds-hp6xx.o
 obj-$(CONFIG_LEDS_FSG)                 += leds-fsg.o
+obj-$(CONFIG_LEDS_PCA955X)             += leds-pca955x.o
 
 # LED Triggers
 obj-$(CONFIG_LEDS_TRIGGER_TIMER)       += ledtrig-timer.o
diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c
new file mode 100644 (file)
index 0000000..146c069
--- /dev/null
@@ -0,0 +1,384 @@
+/*
+ * Copyright 2007-2008 Extreme Engineering Solutions, Inc.
+ *
+ * Author: Nate Case <ncase@xes-inc.com>
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License.  See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * LED driver for various PCA955x I2C LED drivers
+ *
+ * Supported devices:
+ *
+ *     Device          Description             7-bit slave address
+ *     ------          -----------             -------------------
+ *     PCA9550         2-bit driver            0x60 .. 0x61
+ *     PCA9551         8-bit driver            0x60 .. 0x67
+ *     PCA9552         16-bit driver           0x60 .. 0x67
+ *     PCA9553/01      4-bit driver            0x62
+ *     PCA9553/02      4-bit driver            0x63
+ *
+ * Philips PCA955x LED driver chips follow a register map as shown below:
+ *
+ *     Control Register                Description
+ *     ----------------                -----------
+ *     0x0                             Input register 0
+ *                                     ..
+ *     NUM_INPUT_REGS - 1              Last Input register X
+ *
+ *     NUM_INPUT_REGS                  Frequency prescaler 0
+ *     NUM_INPUT_REGS + 1              PWM register 0
+ *     NUM_INPUT_REGS + 2              Frequency prescaler 1
+ *     NUM_INPUT_REGS + 3              PWM register 1
+ *
+ *     NUM_INPUT_REGS + 4              LED selector 0
+ *     NUM_INPUT_REGS + 4
+ *         + NUM_LED_REGS - 1          Last LED selector
+ *
+ *  where NUM_INPUT_REGS and NUM_LED_REGS vary depending on how many
+ *  bits the chip supports.
+ */
+
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/leds.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/workqueue.h>
+
+/* LED select registers determine the source that drives LED outputs */
+#define PCA955X_LS_LED_ON      0x0     /* Output LOW */
+#define PCA955X_LS_LED_OFF     0x1     /* Output HI-Z */
+#define PCA955X_LS_BLINK0      0x2     /* Blink at PWM0 rate */
+#define PCA955X_LS_BLINK1      0x3     /* Blink at PWM1 rate */
+
+enum pca955x_type {
+       pca9550,
+       pca9551,
+       pca9552,
+       pca9553,
+};
+
+struct pca955x_chipdef {
+       int                     bits;
+       u8                      slv_addr;       /* 7-bit slave address mask */
+       int                     slv_addr_shift; /* Number of bits to ignore */
+};
+
+static struct pca955x_chipdef pca955x_chipdefs[] = {
+       [pca9550] = {
+               .bits           = 2,
+               .slv_addr       = /* 110000x */ 0x60,
+               .slv_addr_shift = 1,
+       },
+       [pca9551] = {
+               .bits           = 8,
+               .slv_addr       = /* 1100xxx */ 0x60,
+               .slv_addr_shift = 3,
+       },
+       [pca9552] = {
+               .bits           = 16,
+               .slv_addr       = /* 1100xxx */ 0x60,
+               .slv_addr_shift = 3,
+       },
+       [pca9553] = {
+               .bits           = 4,
+               .slv_addr       = /* 110001x */ 0x62,
+               .slv_addr_shift = 1,
+       },
+};
+
+static const struct i2c_device_id pca955x_id[] = {
+       { "pca9550", pca9550 },
+       { "pca9551", pca9551 },
+       { "pca9552", pca9552 },
+       { "pca9553", pca9553 },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, pca955x_id);
+
+struct pca955x_led {
+       struct pca955x_chipdef  *chipdef;
+       struct i2c_client       *client;
+       struct work_struct      work;
+       spinlock_t              lock;
+       enum led_brightness     brightness;
+       struct led_classdev     led_cdev;
+       int                     led_num;        /* 0 .. 15 potentially */
+       char                    name[32];
+};
+
+/* 8 bits per input register */
+static inline int pca95xx_num_input_regs(int bits)
+{
+       return (bits + 7) / 8;
+}
+
+/* 4 bits per LED selector register */
+static inline int pca95xx_num_led_regs(int bits)
+{
+       return (bits + 3)  / 4;
+}
+
+/*
+ * Return an LED selector register value based on an existing one, with
+ * the appropriate 2-bit state value set for the given LED number (0-3).
+ */
+static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state)
+{
+       return (oldval & (~(0x3 << (led_num << 1)))) |
+               ((state & 0x3) << (led_num << 1));
+}
+
+/*
+ * Write to frequency prescaler register, used to program the
+ * period of the PWM output.  period = (PSCx + 1) / 38
+ */
+static void pca955x_write_psc(struct i2c_client *client, int n, u8 val)
+{
+       struct pca955x_led *pca955x = i2c_get_clientdata(client);
+
+       i2c_smbus_write_byte_data(client,
+               pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n,
+               val);
+}
+
+/*
+ * Write to PWM register, which determines the duty cycle of the
+ * output.  LED is OFF when the count is less than the value of this
+ * register, and ON when it is greater.  If PWMx == 0, LED is always OFF.
+ *
+ * Duty cycle is (256 - PWMx) / 256
+ */
+static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val)
+{
+       struct pca955x_led *pca955x = i2c_get_clientdata(client);
+
+       i2c_smbus_write_byte_data(client,
+               pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n,
+               val);
+}
+
+/*
+ * Write to LED selector register, which determines the source that
+ * drives the LED output.
+ */
+static void pca955x_write_ls(struct i2c_client *client, int n, u8 val)
+{
+       struct pca955x_led *pca955x = i2c_get_clientdata(client);
+
+       i2c_smbus_write_byte_data(client,
+               pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n,
+               val);
+}
+
+/*
+ * Read the LED selector register, which determines the source that
+ * drives the LED output.
+ */
+static u8 pca955x_read_ls(struct i2c_client *client, int n)
+{
+       struct pca955x_led *pca955x = i2c_get_clientdata(client);
+
+       return (u8) i2c_smbus_read_byte_data(client,
+               pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n);
+}
+
+static void pca955x_led_work(struct work_struct *work)
+{
+       struct pca955x_led *pca955x;
+       u8 ls;
+       int chip_ls;    /* which LSx to use (0-3 potentially) */
+       int ls_led;     /* which set of bits within LSx to use (0-3) */
+
+       pca955x = container_of(work, struct pca955x_led, work);
+       chip_ls = pca955x->led_num / 4;
+       ls_led = pca955x->led_num % 4;
+
+       ls = pca955x_read_ls(pca955x->client, chip_ls);
+
+       switch (pca955x->brightness) {
+       case LED_FULL:
+               ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON);
+               break;
+       case LED_OFF:
+               ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF);
+               break;
+       case LED_HALF:
+               ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0);
+               break;
+       default:
+               /*
+                * Use PWM1 for all other values.  This has the unwanted
+                * side effect of making all LEDs on the chip share the
+                * same brightness level if set to a value other than
+                * OFF, HALF, or FULL.  But, this is probably better than
+                * just turning off for all other values.
+                */
+               pca955x_write_pwm(pca955x->client, 1, 255-pca955x->brightness);
+               ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1);
+               break;
+       }
+
+       pca955x_write_ls(pca955x->client, chip_ls, ls);
+}
+
+void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness value)
+{
+       struct pca955x_led *pca955x;
+
+       pca955x = container_of(led_cdev, struct pca955x_led, led_cdev);
+
+       spin_lock(&pca955x->lock);
+       pca955x->brightness = value;
+
+       /*
+        * Must use workqueue for the actual I/O since I2C operations
+        * can sleep.
+        */
+       schedule_work(&pca955x->work);
+
+       spin_unlock(&pca955x->lock);
+}
+
+static int __devinit pca955x_probe(struct i2c_client *client,
+                                       const struct i2c_device_id *id)
+{
+       struct pca955x_led *pca955x;
+       int i;
+       int err = -ENODEV;
+       struct pca955x_chipdef *chip;
+       struct i2c_adapter *adapter;
+       struct led_platform_data *pdata;
+
+       chip = &pca955x_chipdefs[id->driver_data];
+       adapter = to_i2c_adapter(client->dev.parent);
+       pdata = client->dev.platform_data;
+
+       /* Make sure the slave address / chip type combo given is possible */
+       if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) !=
+           chip->slv_addr) {
+               dev_err(&client->dev, "invalid slave address %02x\n",
+                               client->addr);
+               return -ENODEV;
+       }
+
+       printk(KERN_INFO "leds-pca955x: Using %s %d-bit LED driver at "
+                       "slave address 0x%02x\n",
+                       id->name, chip->bits, client->addr);
+
+       if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
+               return -EIO;
+
+       if (pdata) {
+               if (pdata->num_leds != chip->bits) {
+                       dev_err(&client->dev, "board info claims %d LEDs"
+                                       " on a %d-bit chip\n",
+                                       pdata->num_leds, chip->bits);
+                       return -ENODEV;
+               }
+       }
+
+       for (i = 0; i < chip->bits; i++) {
+               pca955x = kzalloc(sizeof(struct pca955x_led), GFP_KERNEL);
+               if (!pca955x) {
+                       err = -ENOMEM;
+                       goto exit;
+               }
+
+               pca955x->chipdef = chip;
+               pca955x->client = client;
+               pca955x->led_num = i;
+               /* Platform data can specify LED names and default triggers */
+               if (pdata) {
+                       if (pdata->leds[i].name)
+                               snprintf(pca955x->name, 32, "pca955x:%s",
+                                                       pdata->leds[i].name);
+                       if (pdata->leds[i].default_trigger)
+                               pca955x->led_cdev.default_trigger =
+                                       pdata->leds[i].default_trigger;
+               } else {
+                       snprintf(pca955x->name, 32, "pca955x:%d", i);
+               }
+               spin_lock_init(&pca955x->lock);
+
+               pca955x->led_cdev.name = pca955x->name;
+               pca955x->led_cdev.brightness_set =
+                               pca955x_led_set;
+
+               /*
+                * Client data is a pointer to the _first_ pca955x_led
+                * struct
+                */
+               if (i == 0)
+                       i2c_set_clientdata(client, pca955x);
+
+               INIT_WORK(&(pca955x->work), pca955x_led_work);
+
+               led_classdev_register(&client->dev, &(pca955x->led_cdev));
+       }
+
+       /* Turn off LEDs */
+       for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++)
+               pca955x_write_ls(client, i, 0x55);
+
+       /* PWM0 is used for half brightness or 50% duty cycle */
+       pca955x_write_pwm(client, 0, 255-LED_HALF);
+
+       /* PWM1 is used for variable brightness, default to OFF */
+       pca955x_write_pwm(client, 1, 0);
+
+       /* Set to fast frequency so we do not see flashing */
+       pca955x_write_psc(client, 0, 0);
+       pca955x_write_psc(client, 1, 0);
+
+       return 0;
+exit:
+       return err;
+}
+
+static int __devexit pca955x_remove(struct i2c_client *client)
+{
+       struct pca955x_led *pca955x = i2c_get_clientdata(client);
+       int leds = pca955x->chipdef->bits;
+       int i;
+
+       for (i = 0; i < leds; i++) {
+               led_classdev_unregister(&(pca955x->led_cdev));
+               cancel_work_sync(&(pca955x->work));
+               kfree(pca955x);
+               pca955x = pca955x + 1;
+       }
+
+       return 0;
+}
+
+static struct i2c_driver pca955x_driver = {
+       .driver = {
+               .name   = "leds-pca955x",
+               .owner  = THIS_MODULE,
+       },
+       .probe  = pca955x_probe,
+       .remove = __devexit_p(pca955x_remove),
+       .id_table = pca955x_id,
+};
+
+static int __init pca955x_leds_init(void)
+{
+       return i2c_add_driver(&pca955x_driver);
+}
+
+static void __exit pca955x_leds_exit(void)
+{
+       i2c_del_driver(&pca955x_driver);
+}
+
+module_init(pca955x_leds_init);
+module_exit(pca955x_leds_exit);
+
+MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
+MODULE_DESCRIPTION("PCA955x LED driver");
+MODULE_LICENSE("GPL v2");
index e7a5e89932fe4a04bb1dd5e2c512f12c08e1fb1a..d41ccb56146ace0077cf09b2add2a5c6209a266b 100644 (file)
@@ -118,6 +118,20 @@ extern void ledtrig_ide_activity(void);
 #define ledtrig_ide_activity() do {} while(0)
 #endif
 
+/*
+ * Generic LED platform data for describing LED names and default triggers.
+ */
+struct led_info {
+       const char      *name;
+       char            *default_trigger;
+       int             flags;
+};
+
+struct led_platform_data {
+       int             num_leds;
+       struct led_info *leds;
+};
+
 /* For the leds-gpio driver */
 struct gpio_led {
        const char *name;