/* * 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");