pwm: lpss: Update PWM setting for Broxton

BugLink: http://bugs.launchpad.net/bugs/1520436

For Broxton PWM controller, base unit is defined as 8-bit integer
and 14-bit fraction, so need to update base unit setting to output
wave with right frequency.
Signed-off-by: Qipeng Zha <qipeng.zha@intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
(cherry picked from commit 883e4d07)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/pwm/pwm-lpss.c

@@ -17,6 +17,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
+#include <linux/time.h>
 
 #include "pwm-lpss.h"
 
@@ -24,11 +25,8 @@
 #define PWM_ENABLE			BIT(31)
 #define PWM_SW_UPDATE			BIT(30)
 #define PWM_BASE_UNIT_SHIFT		8
-#define PWM_BASE_UNIT_MASK		0x00ffff00
 #define PWM_ON_TIME_DIV_MASK		0x000000ff
 #define PWM_DIVISION_CORRECTION		0x2
-#define PWM_LIMIT			(0x8000 + PWM_DIVISION_CORRECTION)
-#define NSECS_PER_SEC			1000000000UL
 
 /* Size of each PWM register space if multiple */
 #define PWM_SIZE			0x400
@@ -36,13 +34,14 @@
 struct pwm_lpss_chip {
 	struct pwm_chip chip;
 	void __iomem *regs;
-	unsigned long clk_rate;
+	const struct pwm_lpss_boardinfo *info;
 };
 
 /* BayTrail */
 const struct pwm_lpss_boardinfo pwm_lpss_byt_info = {
 	.clk_rate = 25000000,
 	.npwm = 1,
+	.base_unit_bits = 16,
 };
 EXPORT_SYMBOL_GPL(pwm_lpss_byt_info);
 
@@ -50,6 +49,7 @@ EXPORT_SYMBOL_GPL(pwm_lpss_byt_info);
 const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
 	.clk_rate = 19200000,
 	.npwm = 1,
+	.base_unit_bits = 16,
 };
 EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info);
 
@@ -57,6 +57,7 @@ EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info);
 const struct pwm_lpss_boardinfo pwm_lpss_bxt_info = {
 	.clk_rate = 19200000,
 	.npwm = 4,
+	.base_unit_bits = 22,
 };
 EXPORT_SYMBOL_GPL(pwm_lpss_bxt_info);
 
@@ -84,23 +85,25 @@ static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
 {
 	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
 	u8 on_time_div;
-	unsigned long c;
-	unsigned long long base_unit, freq = NSECS_PER_SEC;
+	unsigned long c, base_unit_range;
+	unsigned long long base_unit, freq = NSEC_PER_SEC;
 	u32 ctrl;
 
 	do_div(freq, period_ns);
 
-	/* The equation is: base_unit = ((freq / c) * 65536) + correction */
-	base_unit = freq * 65536;
+	/*
+	 * The equation is:
+	 * base_unit = ((freq / c) * base_unit_range) + correction
+	 */
+	base_unit_range = BIT(lpwm->info->base_unit_bits);
+	base_unit = freq * base_unit_range;
 
-	c = lpwm->clk_rate;
+	c = lpwm->info->clk_rate;
 	if (!c)
 		return -EINVAL;
 
 	do_div(base_unit, c);
 	base_unit += PWM_DIVISION_CORRECTION;
-	if (base_unit > PWM_LIMIT)
-		return -EINVAL;
 
 	if (duty_ns <= 0)
 		duty_ns = 1;
@@ -109,8 +112,10 @@ static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	pm_runtime_get_sync(chip->dev);
 
 	ctrl = pwm_lpss_read(pwm);
-	ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
-	ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
+	ctrl &= ~PWM_ON_TIME_DIV_MASK;
+	ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT);
+	base_unit &= (base_unit_range - 1);
+	ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT;
 	ctrl |= on_time_div;
 	/* request PWM to update on next cycle */
 	ctrl |= PWM_SW_UPDATE;
@@ -155,7 +160,7 @@ struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
 	if (IS_ERR(lpwm->regs))
 		return ERR_CAST(lpwm->regs);
 
-	lpwm->clk_rate = info->clk_rate;
+	lpwm->info = info;
 	lpwm->chip.dev = dev;
 	lpwm->chip.ops = &pwm_lpss_ops;
 	lpwm->chip.base = -1;

drivers/pwm/pwm-lpss.h

@@ -21,6 +21,7 @@ struct pwm_lpss_chip;
 struct pwm_lpss_boardinfo {
 	unsigned long clk_rate;
 	unsigned int npwm;
+	unsigned long base_unit_bits;
 };
 
 extern const struct pwm_lpss_boardinfo pwm_lpss_byt_info;