/*
* 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>
#include <linux/slab.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);
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);
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,
};
module_i2c_driver(pca955x_driver);
MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
MODULE_DESCRIPTION("PCA955x LED driver");
MODULE_LICENSE("GPL v2");
