linux-kernel - [PATCH v3 2/5] pwm: atmel: add support for controllers with 32 bit counters

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Date:   Mon, 25 Feb 2019 16:44:37 +0000
From:   <Claudiu.Beznea@...rochip.com>
To:     <thierry.reding@...il.com>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <Nicolas.Ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>, <Ludovic.Desroches@...rochip.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-pwm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <Claudiu.Beznea@...rochip.com>
Subject: [PATCH v3 2/5] pwm: atmel: add support for controllers with 32 bit
 counters

From: Claudiu Beznea <claudiu.beznea@...rochip.com>

SAM9X60's PWM controller use 32 bits counters thus it could generate
signals with higher period and duty cycles than the old ones. Prepare the
current driver to be able to work with old controllers (that uses 16 bits
counters) and with the new SAM9X60's controller, by providing counters
information based on compatible string.

Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
---
 drivers/pwm/pwm-atmel.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
index 7e86a5266eb6..647d063562db 100644
--- a/drivers/pwm/pwm-atmel.c
+++ b/drivers/pwm/pwm-atmel.c
@@ -48,15 +48,11 @@
 #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
+#define PRD_MAXV1_PRES		10
 
 struct atmel_pwm_registers {
 	u8 period;
@@ -65,8 +61,14 @@ 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 +127,10 @@ 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 +290,11 @@ 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 +304,11 @@ 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