mfd: Add LP3943 MFD driver

LP3943 has 16 output pins which can be used as GPIO expander and PWM generator.

* Regmap I2C interface for R/W LP3943 registers

* Atomic operations for output pin assignment
  The driver should check whether requested pin is available or not.
  If the pin is already used, pin request returns as a failure.
  A driver data, 'pin_used' is checked when gpio_request() and
  pwm_request() are called. If the pin is available, then pin_used is set.
  And it is cleared when gpio_free() and pwm_free().

* Device tree support
  Compatible strings for GPIO and PWM driver.
  LP3943 platform data is PWM related, so parsing the device tree is
  implemented in the PWM driver.

Signed-off-by: Milo Kim <milo.kim@ti.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 167 insertions, 0 deletions

diff --git a/drivers/mfd/lp3943.c b/drivers/mfd/lp3943.c
new file mode 100644
index 000000000000..e32226836fb4
--- /dev/null
+++ b/drivers/mfd/lp3943.c
@@ -0,0 +1,167 @@
+/*
+ * TI/National Semiconductor LP3943 MFD Core Driver
+ *
+ * Copyright 2013 Texas Instruments
+ *
+ * Author: Milo Kim <milo.kim@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Driver structure:
+ *   LP3943 is an integrated device capable of driving 16 output channels.
+ *   It can be used for a GPIO expander and PWM generators.
+ *
+ *                                   LED control    General usage for a device
+ *                                   ___________   ____________________________
+ *
+ *   LP3943 MFD ---- GPIO expander    leds-gpio        eg) HW enable pin
+ *               |
+ *               --- PWM generator    leds-pwm         eg) PWM input
+ *
+ *   Internal two PWM channels are used for LED dimming effect.
+ *   And each output pin can be used as a GPIO as well.
+ *   The LED functionality can work with GPIOs or PWMs.
+ *   LEDs can be controlled with legacy leds-gpio(static brightness) or
+ *   leds-pwm drivers(dynamic brightness control).
+ *   Alternatively, it can be used for generic GPIO and PWM controller.
+ *   For example, a GPIO is HW enable pin of a device.
+ *   A PWM is input pin of a backlight device.
+ */
+
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/i2c.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/lp3943.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+#define LP3943_MAX_REGISTERS		0x09
+
+/* Register configuration for pin MUX */
+static const struct lp3943_reg_cfg lp3943_mux_cfg[] = {
+	/* address, mask, shift */
+	{ LP3943_REG_MUX0, 0x03, 0 },
+	{ LP3943_REG_MUX0, 0x0C, 2 },
+	{ LP3943_REG_MUX0, 0x30, 4 },
+	{ LP3943_REG_MUX0, 0xC0, 6 },
+	{ LP3943_REG_MUX1, 0x03, 0 },
+	{ LP3943_REG_MUX1, 0x0C, 2 },
+	{ LP3943_REG_MUX1, 0x30, 4 },
+	{ LP3943_REG_MUX1, 0xC0, 6 },
+	{ LP3943_REG_MUX2, 0x03, 0 },
+	{ LP3943_REG_MUX2, 0x0C, 2 },
+	{ LP3943_REG_MUX2, 0x30, 4 },
+	{ LP3943_REG_MUX2, 0xC0, 6 },
+	{ LP3943_REG_MUX3, 0x03, 0 },
+	{ LP3943_REG_MUX3, 0x0C, 2 },
+	{ LP3943_REG_MUX3, 0x30, 4 },
+	{ LP3943_REG_MUX3, 0xC0, 6 },
+};
+
+static struct mfd_cell lp3943_devs[] = {
+	{
+		.name = "lp3943-pwm",
+		.of_compatible = "ti,lp3943-pwm",
+	},
+	{
+		.name = "lp3943-gpio",
+		.of_compatible = "ti,lp3943-gpio",
+	},
+};
+
+int lp3943_read_byte(struct lp3943 *lp3943, u8 reg, u8 *read)
+{
+	int ret;
+	unsigned int val;
+
+	ret = regmap_read(lp3943->regmap, reg, &val);
+	if (ret < 0)
+		return ret;
+
+	*read = (u8)val;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lp3943_read_byte);
+
+int lp3943_write_byte(struct lp3943 *lp3943, u8 reg, u8 data)
+{
+	return regmap_write(lp3943->regmap, reg, data);
+}
+EXPORT_SYMBOL_GPL(lp3943_write_byte);
+
+int lp3943_update_bits(struct lp3943 *lp3943, u8 reg, u8 mask, u8 data)
+{
+	return regmap_update_bits(lp3943->regmap, reg, mask, data);
+}
+EXPORT_SYMBOL_GPL(lp3943_update_bits);
+
+static const struct regmap_config lp3943_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = LP3943_MAX_REGISTERS,
+};
+
+static int lp3943_probe(struct i2c_client *cl, const struct i2c_device_id *id)
+{
+	struct lp3943 *lp3943;
+	struct device *dev = &cl->dev;
+
+	lp3943 = devm_kzalloc(dev, sizeof(*lp3943), GFP_KERNEL);
+	if (!lp3943)
+		return -ENOMEM;
+
+	lp3943->regmap = devm_regmap_init_i2c(cl, &lp3943_regmap_config);
+	if (IS_ERR(lp3943->regmap))
+		return PTR_ERR(lp3943->regmap);
+
+	lp3943->pdata = dev_get_platdata(dev);
+	lp3943->dev = dev;
+	lp3943->mux_cfg = lp3943_mux_cfg;
+	i2c_set_clientdata(cl, lp3943);
+
+	return mfd_add_devices(dev, -1, lp3943_devs, ARRAY_SIZE(lp3943_devs),
+			       NULL, 0, NULL);
+}
+
+static int lp3943_remove(struct i2c_client *cl)
+{
+	struct lp3943 *lp3943 = i2c_get_clientdata(cl);
+
+	mfd_remove_devices(lp3943->dev);
+	return 0;
+}
+
+static const struct i2c_device_id lp3943_ids[] = {
+	{ "lp3943", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lp3943_ids);
+
+#ifdef CONFIG_OF
+static const struct of_device_id lp3943_of_match[] = {
+	{ .compatible = "ti,lp3943", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, lp3943_of_match);
+#endif
+
+static struct i2c_driver lp3943_driver = {
+	.probe = lp3943_probe,
+	.remove = lp3943_remove,
+	.driver = {
+		.name = "lp3943",
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(lp3943_of_match),
+	},
+	.id_table = lp3943_ids,
+};
+
+module_i2c_driver(lp3943_driver);
+
+MODULE_DESCRIPTION("LP3943 MFD Core Driver");
+MODULE_AUTHOR("Milo Kim");
+MODULE_LICENSE("GPL");