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Subject[PATCH 2/4] pwm: atmel: add support for controllers with 32 bit counters
Date
From: Claudiu Beznea <claudiu.beznea@microchip.com>

New SAM9X60's PWM controller use 32 bits counters thus it could generate
signals with higher period and duty cycles. Update the current driver
to work with old controller (that uses 16 bits counters) and with the
new SAM9X60's controller.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
drivers/pwm/pwm-atmel.c | 38 +++++++++++++++++++++++++++-----------
1 file changed, 27 insertions(+), 11 deletions(-)

diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
index 7e86a5266eb6..44f4a1c9f60b 100644
--- a/drivers/pwm/pwm-atmel.c
+++ b/drivers/pwm/pwm-atmel.c
@@ -48,15 +48,15 @@
#define PWMV2_CPRD 0x0C
#define PWMV2_CPRDUPD 0x10

-/*
- * Max value for duty and period
- *
- * Although the duty and period register is 32 bit,
- * however only the LSB 16 bits are significant.
- */
-#define PWM_MAX_DTY 0xFFFF
-#define PWM_MAX_PRD 0xFFFF
-#define PRD_MAX_PRES 10
+/* Max values for period and prescaler */
+
+/* Only the LSB 16 bits are significant. */
+#define PWM_MAXV1_PRD 0xFFFF
+
+/* All 32 bits are significant. */
+#define PWM_MAXV2_PRD 0xFFFFFFFF
+
+#define PRD_MAXV1_PRES 10

struct atmel_pwm_registers {
u8 period;
@@ -65,8 +65,14 @@ struct atmel_pwm_registers {
u8 duty_upd;
};

+struct atmel_pwm_config {
+ u32 max_period;
+ u32 max_pres;
+};
+
struct atmel_pwm_data {
struct atmel_pwm_registers regs;
+ struct atmel_pwm_config cfg;
};

struct atmel_pwm_chip {
@@ -125,10 +131,10 @@ static int atmel_pwm_calculate_cprd_and_pres(struct pwm_chip *chip,
cycles *= clk_get_rate(atmel_pwm->clk);
do_div(cycles, NSEC_PER_SEC);

- for (*pres = 0; cycles > PWM_MAX_PRD; cycles >>= 1)
+ for (*pres = 0; cycles > atmel_pwm->data->cfg.max_period; cycles >>= 1)
(*pres)++;

- if (*pres > PRD_MAX_PRES) {
+ if (*pres > atmel_pwm->data->cfg.max_pres) {
dev_err(chip->dev, "pres exceeds the maximum value\n");
return -EINVAL;
}
@@ -288,6 +294,11 @@ static const struct atmel_pwm_data atmel_pwm_data_v1 = {
.duty = PWMV1_CDTY,
.duty_upd = PWMV1_CUPD,
},
+ .cfg = {
+ /* 16 bits to keep period and duty. */
+ .max_period = PWM_MAXV1_PRD,
+ .max_pres = PRD_MAXV1_PRES,
+ },
};

static const struct atmel_pwm_data atmel_pwm_data_v2 = {
@@ -297,6 +308,11 @@ static const struct atmel_pwm_data atmel_pwm_data_v2 = {
.duty = PWMV2_CDTY,
.duty_upd = PWMV2_CDTYUPD,
},
+ .cfg = {
+ /* 16 bits to keep period and duty. */
+ .max_period = PWM_MAXV1_PRD,
+ .max_pres = PRD_MAXV1_PRES,
+ },
};

static const struct platform_device_id atmel_pwm_devtypes[] = {
--
2.7.4
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