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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-03-25 03:53:42 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-03-25 03:53:42 -0300
commit03dd4cb26d967f9588437b0fc9cc0e8353322bb7 (patch)
treefa581f6dc1c0596391690d1f67eceef3af8246dc /drivers/pwm/pwm-lpss.c
parentd4e493caf788ef44982e131ff9c786546904d934 (diff)
Linux-libre 4.5-gnu
Diffstat (limited to 'drivers/pwm/pwm-lpss.c')
-rw-r--r--drivers/pwm/pwm-lpss.c57
1 files changed, 40 insertions, 17 deletions
diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
index 250441040..295b963db 100644
--- a/drivers/pwm/pwm-lpss.c
+++ b/drivers/pwm/pwm-lpss.c
@@ -13,10 +13,12 @@
* published by the Free Software Foundation.
*/
+#include <linux/delay.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>
+#include <linux/time.h>
#include "pwm-lpss.h"
@@ -24,11 +26,8 @@
#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 +35,14 @@
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 +50,7 @@ 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 +58,7 @@ 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);
@@ -79,28 +81,37 @@ static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value)
writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
}
+static void pwm_lpss_update(struct pwm_device *pwm)
+{
+ pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_SW_UPDATE);
+ /* Give it some time to propagate */
+ usleep_range(10, 50);
+}
+
static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
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;
@@ -109,13 +120,20 @@ 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;
pwm_lpss_write(pwm, ctrl);
+ /*
+ * If the PWM is already enabled we need to notify the hardware
+ * about the change by setting PWM_SW_UPDATE.
+ */
+ if (pwm_is_enabled(pwm))
+ pwm_lpss_update(pwm);
+
pm_runtime_put(chip->dev);
return 0;
@@ -124,6 +142,12 @@ static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
pm_runtime_get_sync(chip->dev);
+
+ /*
+ * Hardware must first see PWM_SW_UPDATE before the PWM can be
+ * enabled.
+ */
+ pwm_lpss_update(pwm);
pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE);
return 0;
}
@@ -135,7 +159,6 @@ static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
}
static const struct pwm_ops pwm_lpss_ops = {
- .free = pwm_lpss_disable,
.config = pwm_lpss_config,
.enable = pwm_lpss_enable,
.disable = pwm_lpss_disable,
@@ -156,7 +179,7 @@ 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;