leds: Add support for Philips PCA955x I2C LED drivers

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>

1 files changed, 384 insertions, 0 deletions

diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c
new file mode 100644
index 000000000000..146c06972863
--- /dev/null
+++ b/drivers/leds/leds-pca955x.c
@@ -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");