path: root/drivers/leds/leds-is31fl32xx.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for ISSI IS31FL32xx family of I2C LED controllers
 *
 * Copyright 2015 Allworx Corp.
 *
 * Datasheets:
 *   http://www.issi.com/US/product-analog-fxled-driver.shtml
 *   http://www.si-en.com/product.asp?parentid=890
 */

#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/of.h>

/* Used to indicate a device has no such register */
#define IS31FL32XX_REG_NONE 0xFF

/* Software Shutdown bit in Shutdown Register */
#define IS31FL32XX_SHUTDOWN_SSD_ENABLE  0
#define IS31FL32XX_SHUTDOWN_SSD_DISABLE BIT(0)

/* IS31FL3216 has a number of unique registers */
#define IS31FL3216_CONFIG_REG 0x00
#define IS31FL3216_LIGHTING_EFFECT_REG 0x03
#define IS31FL3216_CHANNEL_CONFIG_REG 0x04

/* Software Shutdown bit in 3216 Config Register */
#define IS31FL3216_CONFIG_SSD_ENABLE  BIT(7)
#define IS31FL3216_CONFIG_SSD_DISABLE 0

#define IS31FL32XX_PWM_FREQUENCY_22KHZ  0x01

/* Registers for IS31FL3293 */
#define IS31FL3293_SHUTDOWN_REG 0x01
#define IS31FL3293_SHUTDOWN_SSD_DISABLE  BIT(0)
#define IS31FL3293_SHUTDOWN_EN1 BIT(4)
#define IS31FL3293_SHUTDOWN_EN2 BIT(5)
#define IS31FL3293_SHUTDOWN_EN3 BIT(6)
#define IS31FL3293_GCC_REG 0x03
#define IS31FL3293_GCC_LEVEL_MAX 0x3f
#define IS31FL3293_CL_REG 0x10
#define IS31FL3293_COLOR_UPDATE_REG 0x27
#define IS31FL3293_COLOR_UPDATE_MAGIC 0xc5
#define IS31FL3293_RESET_REG 0x3c
#define IS31FL3293_RESET_MAGIC 0xc5
#define IS31FL3293_MAX_MICROAMP 20000

struct is31fl32xx_priv;
struct is31fl32xx_led_data {
	struct led_classdev cdev;
	u8 channel; /* 1-based, max priv->cdef->channels */
	u32 max_microamp;
	struct is31fl32xx_priv *priv;
};

struct is31fl32xx_priv {
	const struct is31fl32xx_chipdef *cdef;
	struct i2c_client *client;
	unsigned int num_leds;
	struct is31fl32xx_led_data leds[];
};

/**
 * struct is31fl32xx_chipdef - chip-specific attributes
 * @channels            : Number of LED channels
 * @shutdown_reg        : address of Shutdown register (optional)
 * @pwm_update_reg      : address of PWM Update register
 * @pwm_update_value    : value to write to PWM Update register
 * @global_control_reg  : address of Global Control register (optional)
 * @reset_reg           : address of Reset register (optional)
 * @output_frequency_setting_reg: address of output frequency register (optional)
 * @pwm_register_base   : address of first PWM register
 * @pwm_registers_reversed: : true if PWM registers count down instead of up
 * @led_control_register_base : address of first LED control register (optional)
 * @enable_bits_per_led_control_register: number of LEDs enable bits in each
 * @brightness_steps    : number of brightness steps supported by the chip
 * @reset_func          : pointer to reset function
 * @sw_shutdown_func    : pointer to software shutdown function
 *
 * For all optional register addresses, the sentinel value %IS31FL32XX_REG_NONE
 * indicates that this chip has no such register.
 *
 * If non-NULL, @reset_func will be called during probing to set all
 * necessary registers to a known initialization state. This is needed
 * for chips that do not have a @reset_reg.
 *
 * @enable_bits_per_led_control_register must be >=1 if
 * @led_control_register_base != %IS31FL32XX_REG_NONE.
 */
struct is31fl32xx_chipdef {
	u8	channels;
	u8	shutdown_reg;
	u8	pwm_update_reg;
	u8	pwm_update_value;
	u8	global_control_reg;
	u8	reset_reg;
	u8	output_frequency_setting_reg;
	u8	pwm_register_base;
	bool	pwm_registers_reversed;
	u8	led_control_register_base;
	u8	enable_bits_per_led_control_register;
	u16	brightness_steps;
	int (*reset_func)(struct is31fl32xx_priv *priv);
	int (*sw_shutdown_func)(struct is31fl32xx_priv *priv, bool enable);
};

static int is31fl32xx_write(struct is31fl32xx_priv *priv, u8 reg, u8 val)
{
	int ret;

	dev_dbg(&priv->client->dev, "writing register 0x%02X=0x%02X", reg, val);

	ret =  i2c_smbus_write_byte_data(priv->client, reg, val);
	if (ret) {
		dev_err(&priv->client->dev,
			"register write to 0x%02X failed (error %d)",
			reg, ret);
	}
	return ret;
}

/*
 * Custom reset function for IS31FL3216 because it does not have a RESET
 * register the way that the other IS31FL32xx chips do. We don't bother
 * writing the GPIO and animation registers, because the registers we
 * do write ensure those will have no effect.
 */
static int is31fl3216_reset(struct is31fl32xx_priv *priv)
{
	unsigned int i;
	int ret;

	ret = is31fl32xx_write(priv, IS31FL3216_CONFIG_REG,
			       IS31FL3216_CONFIG_SSD_ENABLE);
	if (ret)
		return ret;
	for (i = 0; i < priv->cdef->channels; i++) {
		ret = is31fl32xx_write(priv, priv->cdef->pwm_register_base+i,
				       0x00);
		if (ret)
			return ret;
	}
	ret = is31fl32xx_write(priv, priv->cdef->pwm_update_reg, 0);
	if (ret)
		return ret;
	ret = is31fl32xx_write(priv, IS31FL3216_LIGHTING_EFFECT_REG, 0x00);
	if (ret)
		return ret;
	ret = is31fl32xx_write(priv, IS31FL3216_CHANNEL_CONFIG_REG, 0x00);
	if (ret)
		return ret;

	return 0;
}

/*
 * Custom Software-Shutdown function for IS31FL3216 because it does not have
 * a SHUTDOWN register the way that the other IS31FL32xx chips do.
 * We don't bother doing a read/modify/write on the CONFIG register because
 * we only ever use a value of '0' for the other fields in that register.
 */
static int is31fl3216_software_shutdown(struct is31fl32xx_priv *priv,
					bool enable)
{
	u8 value = enable ? IS31FL3216_CONFIG_SSD_ENABLE :
			    IS31FL3216_CONFIG_SSD_DISABLE;

	return is31fl32xx_write(priv, IS31FL3216_CONFIG_REG, value);
}

/*
 * Custom Reset function for IS31FL3293. We need to set the global current limit
 * and write to the color update register once.
 */
static int is31fl3293_reset(struct is31fl32xx_priv *priv)
{
	int i, ret;

	ret = is31fl32xx_write(priv, IS31FL3293_RESET_REG,
			       IS31FL3293_RESET_MAGIC);
	if (ret)
		return ret;

	/* Set the global current limit to maximum */
	ret = is31fl32xx_write(priv, IS31FL3293_GCC_REG,
			       IS31FL3293_GCC_LEVEL_MAX);
	if (ret)
		return ret;

	for (i = 0; i < priv->num_leds; i++) {
		struct is31fl32xx_led_data *led_data = &priv->leds[i];
		int current_level_reg = IS31FL3293_CL_REG + led_data->channel - 1;
		int microamp = max(led_data->max_microamp, IS31FL3293_MAX_MICROAMP);
		int current_level = (microamp * 0xff) / IS31FL3293_MAX_MICROAMP;

		ret = is31fl32xx_write(priv, current_level_reg, current_level);
		if (ret)
			return ret;
	}

	ret = is31fl32xx_write(priv, IS31FL3293_COLOR_UPDATE_REG,
			       IS31FL3293_COLOR_UPDATE_MAGIC);
	if (ret)
		return ret;

	return 0;
}

/*
 * Custom Software-Shutdown function for IS31FL3293 because the SHUTDOWN
 * register of this device also has bits to enable the channels.
 */
static int is31fl3293_software_shutdown(struct is31fl32xx_priv *priv,
					bool enable)
{
	u8 value = 0;

	if (!enable)
		value =	IS31FL3293_SHUTDOWN_SSD_DISABLE |
			IS31FL3293_SHUTDOWN_EN1 |
			IS31FL3293_SHUTDOWN_EN2 |
			IS31FL3293_SHUTDOWN_EN3;

	return is31fl32xx_write(priv, IS31FL3293_SHUTDOWN_REG, value);
}

/*
 * NOTE: A mutex is not needed in this function because:
 * - All referenced data is read-only after probe()
 * - The I2C core has a mutex on to protect the bus
 * - There are no read/modify/write operations
 * - Intervening operations between the write of the PWM register
 *   and the Update register are harmless.
 *
 * Example:
 *	PWM_REG_1 write 16
 *	UPDATE_REG write 0
 *	PWM_REG_2 write 128
 *	UPDATE_REG write 0
 *   vs:
 *	PWM_REG_1 write 16
 *	PWM_REG_2 write 128
 *	UPDATE_REG write 0
 *	UPDATE_REG write 0
 * are equivalent. Poking the Update register merely applies all PWM
 * register writes up to that point.
 */
static int is31fl32xx_brightness_set(struct led_classdev *led_cdev,
				     enum led_brightness brightness)
{
	const struct is31fl32xx_led_data *led_data =
		container_of(led_cdev, struct is31fl32xx_led_data, cdev);
	const struct is31fl32xx_chipdef *cdef = led_data->priv->cdef;
	u8 pwm_register_offset;
	int ret;

	dev_dbg(led_cdev->dev, "%s: %d\n", __func__, brightness);

	/* NOTE: led_data->channel is 1-based */
	if (cdef->pwm_registers_reversed)
		pwm_register_offset = cdef->channels - led_data->channel;
	else
		pwm_register_offset = led_data->channel - 1;

	switch (cdef->brightness_steps) {
	case 256:
		ret = is31fl32xx_write(led_data->priv,
				       cdef->pwm_register_base + pwm_register