[PATCH v4 1/4] pwm: jz4740: Use clocks from TCU driver

* [PATCH v4 1/4] pwm: jz4740: Use clocks from TCU driver
@ 2020-03-23 14:24 Paul Cercueil
  2020-03-23 14:24 ` [PATCH v4 2/4] pwm: jz4740: Improve algorithm of clock calculation Paul Cercueil
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Paul Cercueil @ 2020-03-23 14:24 UTC (permalink / raw)
  To: Thierry Reding, Uwe Kleine-König
  Cc: od, linux-pwm, linux-kernel, Paul Cercueil, Mathieu Malaterre,
	Artur Rojek

The ingenic-timer "TCU" driver provides us with clocks, that can be
(un)gated, reparented or reclocked from devicetree, instead of having
these settings hardcoded in this driver.

The new code now uses a clk pointer per PWM (instead of a clk per
pwm-chip before). So the pointer is stored in per-pwm data now.
The calls to arch-specific timer code is replaced with standard
clock API calls to start and stop each channel's clock.

While this driver is devicetree-compatible, it is never (as of now)
probed from devicetree, so this change does not introduce a ABI problem
with current devicetree files.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: Mathieu Malaterre <malat@debian.org>
Tested-by: Artur Rojek <contact@artur-rojek.eu>
---

Notes:
    v2: This patch is now before the patch introducing regmap, so the code
    	has changed a bit.
    v3: - Use %pe printf specifier to print error
    	- Update commit message
    	- Removed call to jz4740_timer_set_ctrl() in jz4740_pwm_free() which
    	  was reseting the clock's parent.
    v4: No change

 drivers/pwm/Kconfig      |  1 +
 drivers/pwm/pwm-jz4740.c | 53 +++++++++++++++++++++++++++++-----------
 2 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 30190beeb6e9..69f00eb9bd36 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -225,6 +225,7 @@ config PWM_IMX_TPM
 config PWM_JZ4740
 	tristate "Ingenic JZ47xx PWM support"
 	depends on MACH_INGENIC
+	depends on COMMON_CLK
 	help
 	  Generic PWM framework driver for Ingenic JZ47xx based
 	  machines.
diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c
index 9d78cc21cb12..ee50ac5fabb6 100644
--- a/drivers/pwm/pwm-jz4740.c
+++ b/drivers/pwm/pwm-jz4740.c
@@ -24,7 +24,6 @@
 
 struct jz4740_pwm_chip {
 	struct pwm_chip chip;
-	struct clk *clk;
 };
 
 static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
@@ -34,6 +33,11 @@ static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
 
 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 {
+	struct jz4740_pwm_chip *jz = to_jz4740(chip);
+	struct clk *clk;
+	char clk_name[16];
+	int ret;
+
 	/*
 	 * Timers 0 and 1 are used for system tasks, so they are unavailable
 	 * for use as PWMs.
@@ -41,16 +45,32 @@ static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 	if (pwm->hwpwm < 2)
 		return -EBUSY;
 
-	jz4740_timer_start(pwm->hwpwm);
+	snprintf(clk_name, sizeof(clk_name), "timer%u", pwm->hwpwm);
+
+	clk = clk_get(chip->dev, clk_name);
+	if (IS_ERR(clk)) {
+		if (PTR_ERR(clk) != -EPROBE_DEFER)
+			dev_err(chip->dev, "Failed to get clock: %pe", clk);
+		return PTR_ERR(clk);
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		clk_put(clk);
+		return ret;
+	}
+
+	pwm_set_chip_data(pwm, clk);
 
 	return 0;
 }
 
 static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
-	jz4740_timer_set_ctrl(pwm->hwpwm, 0);
+	struct clk *clk = pwm_get_chip_data(pwm);
 
-	jz4740_timer_stop(pwm->hwpwm);
+	clk_disable_unprepare(clk);
+	clk_put(clk);
 }
 
 static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
@@ -91,17 +111,22 @@ static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			    const struct pwm_state *state)
 {
 	struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
+	struct clk *clk = pwm_get_chip_data(pwm),
+		   *parent_clk = clk_get_parent(clk);
+	unsigned long rate, period, duty;
 	unsigned long long tmp;
-	unsigned long period, duty;
 	unsigned int prescaler = 0;
 	uint16_t ctrl;
+	int err;
 
-	tmp = (unsigned long long)clk_get_rate(jz4740->clk) * state->period;
+	rate = clk_get_rate(parent_clk);
+	tmp = (unsigned long long)rate * state->period;
 	do_div(tmp, 1000000000);
 	period = tmp;
 
 	while (period > 0xffff && prescaler < 6) {
 		period >>= 2;
+		rate >>= 2;
 		++prescaler;
 	}
 
@@ -117,14 +142,18 @@ static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	jz4740_pwm_disable(chip, pwm);
 
+	err = clk_set_rate(clk, rate);
+	if (err) {
+		dev_err(chip->dev, "Unable to set rate: %d", err);
+		return err;
+	}
+
 	jz4740_timer_set_count(pwm->hwpwm, 0);
 	jz4740_timer_set_duty(pwm->hwpwm, duty);
 	jz4740_timer_set_period(pwm->hwpwm, period);
 
-	ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
-		JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
-
-	jz4740_timer_set_ctrl(pwm->hwpwm, ctrl);
+	ctrl = jz4740_timer_get_ctrl(pwm->hwpwm);
+	ctrl |= JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
 
 	switch (state->polarity) {
 	case PWM_POLARITY_NORMAL:
@@ -158,10 +187,6 @@ static int jz4740_pwm_probe(struct platform_device *pdev)
 	if (!jz4740)
 		return -ENOMEM;
 
-	jz4740->clk = devm_clk_get(&pdev->dev, "ext");
-	if (IS_ERR(jz4740->clk))
-		return PTR_ERR(jz4740->clk);
-
 	jz4740->chip.dev = &pdev->dev;
 	jz4740->chip.ops = &jz4740_pwm_ops;
 	jz4740->chip.npwm = NUM_PWM;
-- 
2.25.1


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