Message-Id: <1337355945-16421-1-git-send-email-u.kleine-koenig@pengutronix.de>
Date:	Fri, 18 May 2012 17:45:45 +0200
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	Bryan Wu <bryan.wu@...onical.com>,
	Richard Purdie <rpurdie@...ys.net>
Cc:	kernel@...gutronix.de, linux-kernel@...r.kernel.org
Subject: [PATCH] ARM: leds: Add MAX6956 driver

This adds a driver for Maxim's MAX6956 28-Port LED Display Driver and
I/O Expander.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
---
 drivers/leds/Kconfig                       |   10 +
 drivers/leds/Makefile                      |    1 +
 drivers/leds/leds-max6956.c                |  359 ++++++++++++++++++++++++++++
 include/linux/platform_data/leds-max6956.h |   17 ++
 4 files changed, 387 insertions(+)
 create mode 100644 drivers/leds/leds-max6956.c
 create mode 100644 include/linux/platform_data/leds-max6956.h

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index ff4b8cf..79ef2a1 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -387,6 +387,16 @@ config LEDS_TCA6507
 	  LED driver chips accessed via the I2C bus.
 	  Driver support brightness control and hardware-assisted blinking.
 
+config LEDS_MAX6956
+	tristate "LED support for MAX6956 LED Display Driver and I/O Expander"
+	depends on LEDS_CLASS
+	depends on GPIOLIB
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  This option enables support the LEDs and GPIOs connected to Maxim's
+	  MAX6956 28-Port LED Display Driver and I/O Expander.
+
 config LEDS_MAX8997
 	tristate "LED support for MAX8997 PMIC"
 	depends on LEDS_CLASS && MFD_MAX8997
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 890481c..87ec494 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_LEDS_NS2)			+= leds-ns2.o
 obj-$(CONFIG_LEDS_NETXBIG)		+= leds-netxbig.o
 obj-$(CONFIG_LEDS_ASIC3)		+= leds-asic3.o
 obj-$(CONFIG_LEDS_RENESAS_TPU)		+= leds-renesas-tpu.o
+obj-$(CONFIG_LEDS_MAX6956)		+= leds-max6956.o
 obj-$(CONFIG_LEDS_MAX8997)		+= leds-max8997.o
 
 # LED SPI Drivers
diff --git a/drivers/leds/leds-max6956.c b/drivers/leds/leds-max6956.c
new file mode 100644
index 0000000..976ed91
--- /dev/null
+++ b/drivers/leds/leds-max6956.c
@@ -0,0 +1,359 @@
+/*
+ * Maxim 28-Port LED Display Driver and I/O Expander
+ *
+ * Copyright (C) 2012 Pengutronix
+ * Uwe Kleine-Koenig <u.kleine-koenig@...gutronix.de>
+ *
+ * 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.
+ *
+ * Datasheet: http://datasheets.maxim-ic.com/en/ds/MAX6956.pdf
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/leds.h>
+#include <linux/input.h>
+#include <linux/mutex.h>
+#include <linux/leds-pca9532.h>
+#include <linux/gpio.h>
+#include <linux/regmap.h>
+
+#include <linux/platform_data/leds-max6956.h>
+
+#define MAX6956_REG_GLOBAL_CURRENT		0x02
+#define MAX6956_REG_CONFIGURATION		0x04
+#define MAX6956_REG_CONFIGURATION_S			0x01
+#define MAX6956_REG_CONFIGURATION_I			0x40
+#define MAX6956_REG_CONFIGURATION_M			0x80
+#define MAX6956_REG_TRANSITION_DETECT_MASK	0x06
+#define MAX6956_REG_DISPLAY_TEST		0x07
+/*
+ * MAX6956_REG_PORT_CONFIGURATION(i) holds the configuration for ports
+ * 4 * i, 4 * i + 1, ..., 4 * i + 3 for i in [1, ... 7].
+ */
+#define MAX6956_REG_PORT_CONFIGURATION(i)	(0x08 + (i))
+#define MAX6956_REG_PORT_CONFIGURATION_LED		0x0
+#define MAX6956_REG_PORT_CONFIGURATION_GPIOOUT		0x1
+#define MAX6956_REG_PORT_CONFIGURATION_GPIOINPULLUP	0x2
+#define MAX6956_REG_PORT_CONFIGURATION_GPIOIN		0x3
+/*
+ * MAX6956_REG_CURRENT(i) holds the current for segments 2 * i, 2 * i + 1 for i
+ * in [2, .. 15].
+ */
+#define MAX6956_REG_CURRENT(i)			(0x10 + (i))
+/*
+ * MAX6956_REG_PORT(i) is valid for i in [4, ... 31]. Data bit 0 holds the value
+ * for port i.
+ */
+#define MAX6956_REG_PORT(i)			(0x20 + (i))
+/*
+ * MAX6956_REG_MULTIPORT(i) contains MAX6956_REG_PORT(j) for j in [i, ... i + 7]
+ * for i in [0, ... 31]. Note that data for invalid ports (i.e. 0-3 and 31-38)
+ * read as 0 and writes have no effect.
+ * Note that there is a bug in the documentation (as of revision 2) specifying
+ * that at the high end the data is contained in the lower bits.
+ */
+#define MAX6956_REG_MULTIPORT(i)		(0x40 + (i))
+
+#define MAX6956_NUM_REGISTERS 0x60
+
+struct max6956_led_ddata {
+	unsigned offset;
+	struct led_classdev cdev;
+	struct work_struct work;
+	enum led_brightness brightness;
+};
+
+struct max6956_ddata {
+	struct device *dev;
+
+	struct regmap *regmap;
+
+	struct gpio_chip gpio_chip;
+
+	struct max6956_pdata pdata;
+
+	struct max6956_led_ddata leds[32];
+
+	const char *gpio_names[32];
+};
+
+#define ddata_from_gpio_chip(chip) \
+	container_of(chip, struct max6956_ddata, gpio_chip)
+#define ddata_from_led_cdev(cdev) \
+	dev_get_drvdata(cdev->dev->parent)
+#define ddata_from_work(_work) \
+	ddata_from_led_cdev(&lddata_from_work(_work)->cdev)
+
+#define lddata_from_led_cdev(_cdev) \
+	container_of(_cdev, struct max6956_led_ddata, cdev)
+#define lddata_from_work(_work) \
+	container_of(_work, struct max6956_led_ddata, work)
+
+static const struct regmap_config max6956_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.cache_type = REGCACHE_NONE,
+
+	.max_register = 0x5f,
+};
+
+static int max6956_portconfig_set(struct max6956_ddata *ddata, unsigned offset,
+		unsigned mode)
+{
+	unsigned int reg = MAX6956_REG_PORT_CONFIGURATION(offset / 4);
+	unsigned int shift = 2 * (offset % 4);
+
+	return regmap_update_bits(ddata->regmap, reg,
+			0x3 << shift, mode << shift);
+}
+
+static int max6956_set_sink_current(struct max6956_ddata *ddata,
+		unsigned offset, unsigned regcurrent)
+{
+	unsigned reg = MAX6956_REG_CURRENT(offset / 2);
+	unsigned shift = offset & 1 ? 4 : 0;
+
+	return regmap_update_bits(ddata->regmap, reg,
+			0xf << shift, (regcurrent - 1) << shift);
+}
+
+static void max6956_led_work(struct work_struct *work)
+{
+	struct max6956_led_ddata *lddata = lddata_from_work(work);
+	struct led_classdev *led_cdev = &lddata->cdev;
+
+	struct max6956_ddata *ddata = ddata_from_led_cdev(led_cdev);
+
+	BUG_ON(&ddata->leds[lddata->offset] != lddata);
+
+	if (!lddata->brightness) {
+		regmap_write(ddata->regmap,
+				MAX6956_REG_PORT(lddata->offset), 0);
+	} else {
+		max6956_set_sink_current(ddata, lddata->offset,
+				lddata->brightness);
+		regmap_write(ddata->regmap,
+				MAX6956_REG_PORT(lddata->offset), 1);
+	}
+	max6956_portconfig_set(ddata, lddata->offset, 0);
+}
+
+static unsigned max6956_get_sink_current(struct max6956_ddata *ddata,
+		unsigned offset)
+{
+	unsigned reg = MAX6956_REG_CURRENT(offset / 2);
+	unsigned shift = offset & 1 ? 4 : 0;
+	unsigned regcurrent;
+
+	regmap_read(ddata->regmap, reg, &regcurrent);
+
+	return ((regcurrent >> shift) & 0xf) + 1;
+}
+
+static void max6956_led_brightness_set(struct led_classdev *led_cdev,
+		enum led_brightness brightness)
+{
+	struct max6956_led_ddata *lddata = lddata_from_led_cdev(led_cdev);
+	lddata->brightness = brightness;
+	schedule_work(&lddata->work);
+}
+
+static enum led_brightness max6956_led_brightness_get(
+		struct led_classdev *led_cdev)
+{
+	struct max6956_led_ddata *lddata = lddata_from_led_cdev(led_cdev);
+	struct max6956_ddata *ddata = ddata_from_led_cdev(led_cdev);
+	unsigned val;
+
+	BUG_ON(&ddata->leds[lddata->offset] != lddata);
+
+	regmap_read(ddata->regmap, MAX6956_REG_PORT(lddata->offset), &val);
+
+	if (!(val & 1))
+		return 0;
+
+	return max6956_get_sink_current(ddata, lddata->offset);
+}
+
+static int max6956_gpio_request(struct gpio_chip *chip, unsigned offset)
+{
+	struct max6956_ddata *ddata = ddata_from_gpio_chip(chip);
+	unsigned char type = ddata->pdata.led_pdata[offset].type;
+
+	if (type != MAX6956_TYPE_GPIO && type != MAX6956_TYPE_GPIOPULLUP)
+		return -EBUSY;
+
+	return 0;
+}
+
+static int max6956_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+	struct max6956_ddata *ddata = ddata_from_gpio_chip(chip);
+	unsigned mode;
+
+	switch (ddata->pdata.led_pdata[offset].type) {
+	case MAX6956_TYPE_GPIO:
+		mode = MAX6956_REG_PORT_CONFIGURATION_GPIOIN;
+		break;
+	case MAX6956_TYPE_GPIOPULLUP:
+		mode = MAX6956_REG_PORT_CONFIGURATION_GPIOINPULLUP;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return max6956_portconfig_set(ddata, offset, mode);
+}
+
+static int max6956_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct max6956_ddata *ddata = ddata_from_gpio_chip(chip);
+	unsigned int val;
+
+	regmap_read(ddata->regmap, MAX6956_REG_PORT(offset), &val);
+
+	return val;
+}
+
+static int max6956_gpio_direction_output(struct gpio_chip *chip,
+		unsigned offset, int value)
+{
+	struct max6956_ddata *ddata = ddata_from_gpio_chip(chip);
+
+	regmap_write(ddata->regmap, MAX6956_REG_PORT(offset), !!value);
+
+	return max6956_portconfig_set(ddata, offset,
+			MAX6956_REG_PORT_CONFIGURATION_GPIOOUT);
+}
+
+static void max6956_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct max6956_ddata *ddata = ddata_from_gpio_chip(chip);
+
+	regmap_write(ddata->regmap, MAX6956_REG_PORT(offset), !!value);
+}
+
+static const struct gpio_chip max6956_gpio_chip_init __devinitconst = {
+	.label = "max6956",
+	.owner = THIS_MODULE,
+	.request = max6956_gpio_request,
+	.direction_input = max6956_gpio_direction_input,
+	.get = max6956_gpio_get,
+	.direction_output = max6956_gpio_direction_output,
+	.set = max6956_gpio_set,
+	.base = -1,
+	.ngpio = 32,
+	.can_sleep = 1,
+};
+
+static int __devinit max6956_probe(struct i2c_client *client,
+		const struct i2c_device_id *id)
+{
+	struct max6956_ddata *ddata;
+	struct max6956_pdata *pdata = client->dev.platform_data;
+	int ret, i;
+
+	if (!pdata)
+		return -EINVAL;
+
+	ddata = devm_kzalloc(&client->dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata) {
+		dev_err(&client->dev, "Failed to allocate driver private data\n");
+		return -ENOMEM;
+	}
+
+	ddata->dev = &client->dev;
+	ddata->regmap = devm_regmap_init_i2c(client, &max6956_regmap_config);
+	if (IS_ERR(ddata->regmap)) {
+		ret = PTR_ERR(ddata->regmap);
+		dev_err(ddata->dev, "Failed to allocate register map: %d\n",
+				ret);
+		return ret;
+	}
+	ddata->pdata = *pdata;
+	i2c_set_clientdata(client, ddata);
+
+	ddata->gpio_chip = max6956_gpio_chip_init;
+	ddata->gpio_chip.names = ddata->gpio_names;
+	ddata->gpio_chip.dev = ddata->dev;
+
+	regmap_write(ddata->regmap, MAX6956_REG_CONFIGURATION,
+			MAX6956_REG_CONFIGURATION_S |
+			MAX6956_REG_CONFIGURATION_I);
+
+	for (i = 4; i < 32; ++i)
+		switch (pdata->led_pdata[i].type) {
+		case MAX6956_TYPE_GPIO:
+		case MAX6956_TYPE_GPIOPULLUP:
+			ddata->gpio_names[i] = pdata->led_pdata[i].name;
+			break;
+		case MAX6956_TYPE_LED:
+			ddata->leds[i] = (struct max6956_led_ddata){
+				.offset = i,
+				.cdev = {
+					.name = pdata->led_pdata[i].name,
+					.max_brightness = 16,
+					.brightness_set =
+						max6956_led_brightness_set,
+					.brightness_get =
+						max6956_led_brightness_get,
+				},
+			};
+			INIT_WORK(&ddata->leds[i].work, max6956_led_work);
+
+			ret = led_classdev_register(ddata->dev,
+					&ddata->leds[i].cdev);
+			if (ret)
+				dev_warn(ddata->dev,
+						"Failed to register led %s\n",
+						pdata->led_pdata[i].name);
+			break;
+		}
+
+	ret = gpiochip_add(&ddata->gpio_chip);
+
+	return ret;
+}
+
+static int __devexit max6956_remove(struct i2c_client *client)
+{
+	struct max6956_ddata *ddata = i2c_get_clientdata(client);
+	int ret, i;
+
+	ret = gpiochip_remove(&ddata->gpio_chip);
+	if (ret)
+		dev_warn(ddata->dev, "Failed to remove gpiochip: %d\n", ret);
+
+	for (i = 4; i < 32; ++i)
+		if (ddata->pdata.led_pdata[i].type == MAX6956_TYPE_LED)
+			led_classdev_unregister(&ddata->leds[i].cdev);
+
+	return 0;
+}
+
+static const struct i2c_device_id max6956_device_id[] = {
+	{ "max6956", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(i2c, max6956_device_id);
+
+static struct i2c_driver max6956_driver = {
+	.driver = {
+		.name = "leds-max6956",
+		.owner = THIS_MODULE,
+	},
+	.probe = max6956_probe,
+	.remove = max6956_remove,
+	.id_table = max6956_device_id,
+};
+
+module_i2c_driver(max6956_driver);
+
+MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@...gutronix.de>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MAX6956 LED Display Driver and I/O Expander");
diff --git a/include/linux/platform_data/leds-max6956.h b/include/linux/platform_data/leds-max6956.h
new file mode 100644
index 0000000..c7290a4
--- /dev/null
+++ b/include/linux/platform_data/leds-max6956.h
@@ -0,0 +1,17 @@
+#ifndef __LINUX_PLATFORM_DATA_LEDS_MAX6956_H__
+#define __LINUX_PLATFORM_DATA_LEDS_MAX6956_H__
+
+#define MAX6956_TYPE_GPIO	0
+#define MAX6956_TYPE_GPIOPULLUP	1
+#define MAX6956_TYPE_LED	2
+
+struct max6956_led_pdata {
+	unsigned char type;
+	const char *name;
+};
+
+struct max6956_pdata {
+	struct max6956_led_pdata led_pdata[32];
+};
+
+#endif
-- 
1.7.10

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