mfd: Add support for TWL6030 PWM

TWL6030 supports PWM (Pulse Width Modulator) which is used
to control charging LED. PWM allows for controlling brightness.
This patch implements the APIs required by leds-pwm driver.
Signed-off-by: Hemanth V <hemanthv@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/Kconfig

@@ -186,6 +186,15 @@ config TWL4030_CODEC
 	select MFD_CORE
 	default n
 
+config TWL6030_PWM
+	tristate "TWL6030 PWM (Pulse Width Modulator) Support"
+	depends on TWL4030_CORE
+	select HAVE_PWM
+	default n
+	help
+	  Say yes here if you want support for TWL6030 PWM.
+	  This is used to control charging LED brightness.
+
 config MFD_STMPE
 	bool "Support STMicroelectronics STMPE"
 	depends on I2C=y && GENERIC_HARDIRQS

drivers/mfd/Makefile

@@ -37,6 +37,7 @@ obj-$(CONFIG_MENELAUS)		+= menelaus.o
 obj-$(CONFIG_TWL4030_CORE)	+= twl-core.o twl4030-irq.o twl6030-irq.o
 obj-$(CONFIG_TWL4030_POWER)    += twl4030-power.o
 obj-$(CONFIG_TWL4030_CODEC)	+= twl4030-codec.o
+obj-$(CONFIG_TWL6030_PWM)	+= twl6030-pwm.o
 
 obj-$(CONFIG_MFD_MC13783)	+= mc13783-core.o
 

drivers/mfd/twl6030-pwm.c

+/*
+ * twl6030_pwm.c
+ * Driver for PHOENIX (TWL6030) Pulse Width Modulator
+ *
+ * Copyright (C) 2010 Texas Instruments
+ * Author: Hemanth V <hemanthv@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.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/i2c/twl.h>
+#include <linux/slab.h>
+
+#define LED_PWM_CTRL1	0xF4
+#define LED_PWM_CTRL2	0xF5
+
+/* Max value for CTRL1 register */
+#define PWM_CTRL1_MAX	255
+
+/* Pull down disable */
+#define PWM_CTRL2_DIS_PD	(1 << 6)
+
+/* Current control 2.5 milli Amps */
+#define PWM_CTRL2_CURR_02	(2 << 4)
+
+/* LED supply source */
+#define PWM_CTRL2_SRC_VAC	(1 << 2)
+
+/* LED modes */
+#define PWM_CTRL2_MODE_HW	(0 << 0)
+#define PWM_CTRL2_MODE_SW	(1 << 0)
+#define PWM_CTRL2_MODE_DIS	(2 << 0)
+
+#define PWM_CTRL2_MODE_MASK	0x3
+
+struct pwm_device {
+	const char *label;
+	unsigned int pwm_id;
+};
+
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+	u8 duty_cycle;
+	int ret;
+
+	if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
+		return -EINVAL;
+
+	duty_cycle = (duty_ns * PWM_CTRL1_MAX) / period_ns;
+
+	ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, duty_cycle, LED_PWM_CTRL1);
+
+	if (ret < 0) {
+		pr_err("%s: Failed to configure PWM, Error %d\n",
+			pwm->label, ret);
+		return ret;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(pwm_config);
+
+int pwm_enable(struct pwm_device *pwm)
+{
+	u8 val;
+	int ret;
+
+	ret = twl_i2c_read_u8(TWL6030_MODULE_ID1, &val, LED_PWM_CTRL2);
+	if (ret < 0) {
+		pr_err("%s: Failed to enable PWM, Error %d\n", pwm->label, ret);
+		return ret;
+	}
+
+	/* Change mode to software control */
+	val &= ~PWM_CTRL2_MODE_MASK;
+	val |= PWM_CTRL2_MODE_SW;
+
+	ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, val, LED_PWM_CTRL2);
+	if (ret < 0) {
+		pr_err("%s: Failed to enable PWM, Error %d\n", pwm->label, ret);
+		return ret;
+	}
+
+	twl_i2c_read_u8(TWL6030_MODULE_ID1, &val, LED_PWM_CTRL2);
+	return 0;
+}
+EXPORT_SYMBOL(pwm_enable);
+
+void pwm_disable(struct pwm_device *pwm)
+{
+	u8 val;
+	int ret;
+
+	ret = twl_i2c_read_u8(TWL6030_MODULE_ID1, &val, LED_PWM_CTRL2);
+	if (ret < 0) {
+		pr_err("%s: Failed to disable PWM, Error %d\n",
+			pwm->label, ret);
+		return;
+	}
+
+	val &= ~PWM_CTRL2_MODE_MASK;
+	val |= PWM_CTRL2_MODE_HW;
+
+	ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, val, LED_PWM_CTRL2);
+	if (ret < 0) {
+		pr_err("%s: Failed to disable PWM, Error %d\n",
+			pwm->label, ret);
+		return;
+	}
+	return;
+}
+EXPORT_SYMBOL(pwm_disable);
+
+struct pwm_device *pwm_request(int pwm_id, const char *label)
+{
+	u8 val;
+	int ret;
+	struct pwm_device *pwm;
+
+	pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
+	if (pwm == NULL) {
+		pr_err("%s: failed to allocate memory\n", label);
+		return NULL;
+	}
+
+	pwm->label = label;
+	pwm->pwm_id = pwm_id;
+
+	/* Configure PWM */
+	val = PWM_CTRL2_DIS_PD | PWM_CTRL2_CURR_02 | PWM_CTRL2_SRC_VAC |
+		PWM_CTRL2_MODE_HW;
+
+	ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, val, LED_PWM_CTRL2);
+
+	if (ret < 0) {
+		pr_err("%s: Failed to configure PWM, Error %d\n",
+			 pwm->label, ret);
+
+		kfree(pwm);
+		return NULL;
+	}
+
+	return pwm;
+}
+EXPORT_SYMBOL(pwm_request);
+
+void pwm_free(struct pwm_device *pwm)
+{
+	pwm_disable(pwm);
+	kfree(pwm);
+}
+EXPORT_SYMBOL(pwm_free);