misc: add PWM (Pulse Width Modulation) driver for pmic8058 chip

Qualcomm PM8058 chip has 8 channels of PWM, also called LPG (Light
Pulse Generator). All PWM channels can be used as simple PWM machine
or as a more advanced PWM pattern generator using programmed lookup
table. This patch supports simple PWM machine as a sub device of
pmic8058 core.

To use PWM:
1. #include <linux/pwm.h>
2. #include <linux/pmic8058-pwm.h> only when you want to do the
   configuration by yourself.
3. First call
   * pwm_request() -- to reserve a PWM chanel
4. Call these APIs to configure & start/stop a PWM waveform
   * pwm_config(period, duty) -- to configure a PWM wave
   * pwm_enable() -- to start and enable the PWM output
   * pwm_disable() -- to stop and disable the PWM output
   You can repeat above 3 calls for different PWM waveforms.
5. Last call
   * pwm_free() -- to free the PWM channel

Signed-off-by: Willie Ruan <wruan@quicinc.com>

drivers/misc/Kconfig

@@ -566,6 +566,16 @@ config HAPTIC_ISA1200
 	help
 	  The ISA1200 is a high performance enhanced haptic driver.
 
+config PMIC8058_PWM
+	tristate "Qualcomm PM8058 PWM support"
+	depends on PMIC8058
+	default y
+	help
+	  This option enables device driver support for the PWM channels
+	  on Qualcomm PM8058 chip. Pulse Width Modulation is used for
+	  purposes including software controlled brightness of backlight,
+	  motor control, and waveform generation.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"

drivers/misc/Makefile

@@ -57,3 +57,4 @@ msm_tsif-objs := tsif.o
 obj-$(CONFIG_TSIF_CHRDEV) += tsif_chrdev.o
 obj-$(CONFIG_TSPP) += tspp.o
 obj-$(CONFIG_HAPTIC_ISA1200)		+= isa1200.o
+obj-$(CONFIG_PMIC8058_PWM) += pmic8058-pwm.o

include/linux/pmic8058-pwm.h

@@ -0,0 +1,148 @@
+/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only 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.
+ *
+ */
+#ifndef __PMIC8058_PWM_H__
+#define __PMIC8058_PWM_H__
+
+/* The MAX value is computation limit. Hardware limit is 393 seconds. */
+#define	PM_PWM_PERIOD_MAX		(274 * USEC_PER_SEC)
+/* The MIN value is hardware limit. */
+#define	PM_PWM_PERIOD_MIN		7 /* micro seconds */
+
+struct pm8058_pwm_pdata {
+	int 	(*config)(struct pwm_device *pwm, int ch, int on);
+	int 	(*enable)(struct pwm_device *pwm, int ch, int on);
+};
+
+#define	PM_PWM_LUT_SIZE			64
+#define	PM_PWM_LUT_DUTY_TIME_MAX	512	/* ms */
+#define	PM_PWM_LUT_PAUSE_MAX		(7000 * PM_PWM_LUT_DUTY_TIME_MAX)
+
+/* Flags for Look Up Table */
+#define	PM_PWM_LUT_LOOP		0x01
+#define	PM_PWM_LUT_RAMP_UP	0x02
+#define	PM_PWM_LUT_REVERSE	0x04
+#define	PM_PWM_LUT_PAUSE_HI_EN	0x10
+#define	PM_PWM_LUT_PAUSE_LO_EN	0x20
+
+#define	PM_PWM_LUT_NO_TABLE	0x100
+
+/* PWM LED ID */
+#define	PM_PWM_LED_0		0
+#define	PM_PWM_LED_1		1
+#define	PM_PWM_LED_2		2
+#define	PM_PWM_LED_KPD		3
+#define	PM_PWM_LED_FLASH	4
+#define	PM_PWM_LED_FLASH1	5
+
+/* PWM LED configuration mode */
+#define	PM_PWM_CONF_NONE	0x0
+#define	PM_PWM_CONF_PWM1	0x1
+#define	PM_PWM_CONF_PWM2	0x2
+#define	PM_PWM_CONF_PWM3	0x3
+#define	PM_PWM_CONF_DTEST1	0x4
+#define	PM_PWM_CONF_DTEST2	0x5
+#define	PM_PWM_CONF_DTEST3	0x6
+#define	PM_PWM_CONF_DTEST4	0x7
+
+/**
+ * PWM frequency/period control
+ *
+ * PWM Frequency = ClockFrequency / (N * T)
+ *   or
+ * PWM Period = Clock Period * (N * T)
+ *   where
+ * N = 2^9 or 2^6 for 9-bit or 6-bit PWM size
+ * T = Pre-divide * 2^m, m = 0..7 (exponent)
+ *
+ */
+
+enum pm_pwm_size {
+	PM_PWM_SIZE_6BIT =	6,
+	PM_PWM_SIZE_9BIT =	9,
+};
+
+enum pm_pwm_clk {
+	PM_PWM_CLK_1KHZ,
+	PM_PWM_CLK_32KHZ,
+	PM_PWM_CLK_19P2MHZ,
+};
+
+enum pm_pwm_pre_div {
+	PM_PWM_PDIV_2,
+	PM_PWM_PDIV_3,
+	PM_PWM_PDIV_5,
+	PM_PWM_PDIV_6,
+};
+
+/**
+ * struct pm8058_pwm_period - PWM period structure
+ * @pwm_size: enum pm_pwm_size
+ * @clk: enum pm_pwm_clk
+ * @pre_div: enum pm_pwm_pre_div
+ * @pre_div_exp: exponent of 2 as part of pre-divider: 0..7
+ */
+struct pm8058_pwm_period {
+	enum pm_pwm_size	pwm_size;
+	enum pm_pwm_clk		clk;
+	enum pm_pwm_pre_div	pre_div;
+	int			pre_div_exp;
+};
+
+/**
+ * pm8058_pwm_config_period - change PWM period
+ *
+ * @pwm: the PWM device
+ * @pwm_p: period in struct pm8058_pwm_period
+ */
+int pm8058_pwm_config_period(struct pwm_device *pwm,
+			     struct pm8058_pwm_period *pwm_p);
+
+/**
+ * pm8058_pwm_config_duty_cycle - change PWM duty cycle
+ *
+ * @pwm: the PWM device
+ * @pwm_value: the duty cycle in raw PWM value (< 2^pwm_size)
+ */
+int pm8058_pwm_config_duty_cycle(struct pwm_device *pwm, int pwm_value);
+
+/**
+ * pm8058_pwm_lut_config - change a PWM device configuration to use LUT
+ *
+ * @pwm: the PWM device
+ * @period_us: period in micro second
+ * @duty_pct: arrary of duty cycles in percent, like 20, 50.
+ * @duty_time_ms: time for each duty cycle in millisecond
+ * @start_idx: start index in lookup table from 0 to MAX-1
+ * @idx_len: number of index
+ * @pause_lo: pause time in millisecond at low index
+ * @pause_hi: pause time in millisecond at high index
+ * @flags: control flags
+ */
+int pm8058_pwm_lut_config(struct pwm_device *pwm, int period_us,
+			  int duty_pct[], int duty_time_ms, int start_idx,
+			  int len, int pause_lo, int pause_hi, int flags);
+
+/**
+ * pm8058_pwm_lut_enable - control a PWM device to start/stop LUT ramp
+ *
+ * @pwm: the PWM device
+ * @start: to start (1), or stop (0)
+ */
+int pm8058_pwm_lut_enable(struct pwm_device *pwm, int start);
+
+int pm8058_pwm_set_dtest(struct pwm_device *pwm, int enable);
+
+int pm8058_pwm_config_led(struct pwm_device *pwm, int id,
+			  int mode, int max_current);
+
+#endif /* __PMIC8058_PWM_H__ */