diff options
Diffstat (limited to 'drivers/leds/leds-pca955x.c')
| -rw-r--r-- | drivers/leds/leds-pca955x.c | 390 |
1 files changed, 390 insertions, 0 deletions
diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c new file mode 100644 index 0000000..4e2d1a4 --- /dev/null +++ b/drivers/leds/leds-pca955x.c @@ -0,0 +1,390 @@ +/* + * 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); +} + +static 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; + struct pca955x_chipdef *chip; + struct i2c_adapter *adapter; + struct led_platform_data *pdata; + int i, err; + + 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; + } + } + + pca955x = kzalloc(sizeof(*pca955x) * chip->bits, GFP_KERNEL); + if (!pca955x) + return -ENOMEM; + + i2c_set_clientdata(client, pca955x); + + for (i = 0; i < chip->bits; i++) { + pca955x[i].chipdef = chip; + pca955x[i].client = client; + pca955x[i].led_num = i; + + /* Platform data can specify LED names and default triggers */ + if (pdata) { + if (pdata->leds[i].name) + snprintf(pca955x[i].name, + sizeof(pca955x[i].name), "pca955x:%s", + pdata->leds[i].name); + if (pdata->leds[i].default_trigger) + pca955x[i].led_cdev.default_trigger = + pdata->leds[i].default_trigger; + } else { + snprintf(pca955x[i].name, sizeof(pca955x[i].name), + "pca955x:%d", i); + } + + spin_lock_init(&pca955x[i].lock); + + pca955x[i].led_cdev.name = pca955x[i].name; + pca955x[i].led_cdev.brightness_set = pca955x_led_set; + + INIT_WORK(&pca955x[i].work, pca955x_led_work); + + err = led_classdev_register(&client->dev, &pca955x[i].led_cdev); + if (err < 0) + goto exit; + } + + /* 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: + while (i--) { + led_classdev_unregister(&pca955x[i].led_cdev); + cancel_work_sync(&pca955x[i].work); + } + + kfree(pca955x); + i2c_set_clientdata(client, NULL); + + return err; +} + +static int __devexit pca955x_remove(struct i2c_client *client) +{ + struct pca955x_led *pca955x = i2c_get_clientdata(client); + int i; + + for (i = 0; i < pca955x->chipdef->bits; i++) { + led_classdev_unregister(&pca955x[i].led_cdev); + cancel_work_sync(&pca955x[i].work); + } + + kfree(pca955x); + i2c_set_clientdata(client, NULL); + + 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"); |
