[PATCHv9 Resend 0/4] Add Freescale FTM PWM driver

[PATCHv9 Resend 0/4] Add Freescale FTM PWM driver

[Xiubo Li]

Resend this patch series, just adding the missing and new Reviewed-by and
Acked-by infomation of this patch series.


Xiubo Li (4):
  pwm: Add Freescale FTM PWM driver support
  ARM: dts: vf610: Add Freescale FTM PWM node.
  ARM: dts: vf610-twr: Enables FTM PWM device.
  Documentation: Add device tree bindings for Freescale FTM PWM.

 .../devicetree/bindings/pwm/pwm-fsl-ftm.txt        |  34 ++
 arch/arm/boot/dts/vf610-twr.dts                    |   6 +
 arch/arm/boot/dts/vf610.dtsi                       |  13 +
 drivers/pwm/Kconfig                                |  10 +
 drivers/pwm/Makefile                               |   1 +
 drivers/pwm/pwm-fsl-ftm.c                          | 479 +++++++++++++++++++++
 6 files changed, 543 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
 create mode 100644 drivers/pwm/pwm-fsl-ftm.c

-- 
1.8.4

[PATCHv9 Resend 1/4] pwm: Add Freescale FTM PWM driver support

[Xiubo Li]

The FTM PWM device can be found on Vybrid VF610 Tower and
Layerscape LS-1 SoCs.

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Alison Wang <b18965@freescale.com>
Signed-off-by: Jingchang Lu <b35083@freescale.com>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Yuan Yao <yao.yuan@freescale.com>
---
 drivers/pwm/Kconfig       |  10 +
 drivers/pwm/Makefile      |   1 +
 drivers/pwm/pwm-fsl-ftm.c | 479 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 490 insertions(+)
 create mode 100644 drivers/pwm/pwm-fsl-ftm.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 6a2a1e0a..9a4c641 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -80,6 +80,16 @@ config PWM_EP93XX
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-ep93xx.
 
+config PWM_FSL_FTM
+	tristate "Freescale FlexTimer Module (FTM) PWM support"
+	depends on OF
+	help
+	  Generic FTM PWM framework driver for Freescale VF610 and
+	  Layerscape LS-1 SoCs.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-fsl-ftm.
+
 config PWM_IMX
 	tristate "i.MX PWM support"
 	depends on ARCH_MXC
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 1b99cfb..c22905c 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_PWM_ATMEL)		+= pwm-atmel.o
 obj-$(CONFIG_PWM_ATMEL_TCB)	+= pwm-atmel-tcb.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
 obj-$(CONFIG_PWM_EP93XX)	+= pwm-ep93xx.o
+obj-$(CONFIG_PWM_FSL_FTM)	+= pwm-fsl-ftm.o
 obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
 obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
 obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
diff --git a/drivers/pwm/pwm-fsl-ftm.c b/drivers/pwm/pwm-fsl-ftm.c
new file mode 100644
index 0000000..60467b3
--- /dev/null
+++ b/drivers/pwm/pwm-fsl-ftm.c
@@ -0,0 +1,479 @@
+/*
+ *  Freescale FlexTimer Module (FTM) PWM Driver
+ *
+ *  Copyright 2012-2013 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+#define FTM_SC		0x00
+#define FTM_SC_CLK_MASK	0x3
+#define FTM_SC_CLK_SHIFT	3
+#define FTM_SC_CLK(c)	(((c) + 1) << FTM_SC_CLK_SHIFT)
+#define FTM_SC_PS_MASK	0x7
+#define FTM_SC_PS_SHIFT	0
+
+#define FTM_CNT		0x04
+#define FTM_MOD		0x08
+
+#define FTM_CSC_BASE	0x0C
+#define FTM_CSC_MSB	BIT(5)
+#define FTM_CSC_MSA	BIT(4)
+#define FTM_CSC_ELSB	BIT(3)
+#define FTM_CSC_ELSA	BIT(2)
+#define FTM_CSC(_channel)	(FTM_CSC_BASE + ((_channel) * 8))
+
+#define FTM_CV_BASE	0x10
+#define FTM_CV(_channel)	(FTM_CV_BASE + ((_channel) * 8))
+
+#define FTM_CNTIN	0x4C
+#define FTM_STATUS	0x50
+
+#define FTM_MODE	0x54
+#define FTM_MODE_FTMEN	BIT(0)
+#define FTM_MODE_INIT	BIT(2)
+#define FTM_MODE_PWMSYNC	BIT(3)
+
+#define FTM_SYNC	0x58
+#define FTM_OUTINIT	0x5C
+#define FTM_OUTMASK	0x60
+#define FTM_COMBINE	0x64
+#define FTM_DEADTIME	0x68
+#define FTM_EXTTRIG	0x6C
+#define FTM_POL		0x70
+#define FTM_FMS		0x74
+#define FTM_FILTER	0x78
+#define FTM_FLTCTRL	0x7C
+#define FTM_QDCTRL	0x80
+#define FTM_CONF	0x84
+#define FTM_FLTPOL	0x88
+#define FTM_SYNCONF	0x8C
+#define FTM_INVCTRL	0x90
+#define FTM_SWOCTRL	0x94
+#define FTM_PWMLOAD	0x98
+
+enum fsl_pwm_clk {
+	FSL_PWM_CLK_SYS,
+	FSL_PWM_CLK_FIX,
+	FSL_PWM_CLK_EXT,
+};
+
+struct fsl_pwm_chip {
+	struct pwm_chip chip;
+
+	struct mutex lock;
+
+	struct clk *sys_clk;
+	struct clk *counter_clk;
+	struct clk *counter_clk_en;
+	unsigned int counter_clk_select;
+	unsigned int counter_clk_enable;
+	unsigned int clk_ps;
+
+	void __iomem *base;
+
+	int period_ns;
+};
+
+static inline struct fsl_pwm_chip *to_fsl_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct fsl_pwm_chip, chip);
+}
+
+static int fsl_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
+
+	return clk_prepare_enable(fpc->sys_clk);
+}
+
+static void fsl_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
+
+	clk_disable_unprepare(fpc->sys_clk);
+}
+
+static int fsl_pwm_calculate_default_ps(struct fsl_pwm_chip *fpc,
+					enum fsl_pwm_clk index)
+{
+	unsigned long sys_rate, cnt_rate;
+	unsigned long long ratio;
+
+	sys_rate = clk_get_rate(fpc->sys_clk);
+	if (!sys_rate)
+		return -EINVAL;
+
+	cnt_rate = clk_get_rate(fpc->counter_clk);
+	if (!cnt_rate)
+		return -EINVAL;
+
+	switch (index) {
+	case FSL_PWM_CLK_SYS:
+		fpc->clk_ps = 1;
+		break;
+	case FSL_PWM_CLK_FIX:
+		ratio = 2 * cnt_rate - 1;
+		do_div(ratio, sys_rate);
+		fpc->clk_ps = ratio;
+		break;
+	case FSL_PWM_CLK_EXT:
+		ratio = 4 * cnt_rate - 1;
+		do_div(ratio, sys_rate);
+		fpc->clk_ps = ratio;
+		break;
+	}
+
+	return 0;
+}
+
+static unsigned long fsl_pwm_calculate_cycles(struct fsl_pwm_chip *fpc,
+					      unsigned long period_ns)
+{
+	unsigned long long c, c0;
+
+	c = clk_get_rate(fpc->counter_clk);
+	c = c * period_ns;
+	do_div(c, 1000000000UL);
+
+	do {
+		c0 = c;
+		do_div(c0, (1 << fpc->clk_ps));
+		if (c0 <= 0xFFFF)
+			return (unsigned long)c0;
+	} while (++fpc->clk_ps < 8);
+
+	return 0;
+}
+
+static unsigned long fsl_pwm_calculate_period_cycles(struct fsl_pwm_chip *fpc,
+						     unsigned long period_ns,
+						     enum fsl_pwm_clk index)
+{
+	int ret;
+
+	fpc->counter_clk_select = FTM_SC_CLK(index);
+
+	ret = fsl_pwm_calculate_default_ps(fpc, index);
+	if (ret) {
+		dev_err(fpc->chip.dev, "failed to calculate default "
+				"prescaler: %d\n", ret);
+		return 0;
+	}
+
+	return fsl_pwm_calculate_cycles(fpc, period_ns);
+}
+
+static unsigned long fsl_pwm_calculate_period(struct fsl_pwm_chip *fpc,
+					      unsigned long period_ns)
+{
+	struct clk *cnt_clk[3];
+	enum fsl_pwm_clk m0, m1;
+	unsigned long fix_rate, ext_rate, cycles;
+
+	fpc->counter_clk = fpc->sys_clk;
+	cycles = fsl_pwm_calculate_period_cycles(fpc, period_ns,
+			FSL_PWM_CLK_SYS);
+	if (cycles)
+		return cycles;
+
+	cnt_clk[FSL_PWM_CLK_FIX] = devm_clk_get(fpc->chip.dev, "ftm_fix");
+	if (IS_ERR(cnt_clk[FSL_PWM_CLK_FIX]))
+		return PTR_ERR(cnt_clk[FSL_PWM_CLK_FIX]);
+
+	cnt_clk[FSL_PWM_CLK_EXT] = devm_clk_get(fpc->chip.dev, "ftm_ext");
+	if (IS_ERR(cnt_clk[FSL_PWM_CLK_EXT]))
+		return PTR_ERR(cnt_clk[FSL_PWM_CLK_EXT]);
+
+	fpc->counter_clk_en = devm_clk_get(fpc->chip.dev, "ftm_cnt_clk_en");
+	if (IS_ERR(fpc->counter_clk_en))
+		return PTR_ERR(fpc->counter_clk_en);
+
+	fix_rate = clk_get_rate(cnt_clk[FSL_PWM_CLK_FIX]);
+	ext_rate = clk_get_rate(cnt_clk[FSL_PWM_CLK_EXT]);
+
+	if (fix_rate > ext_rate) {
+		m0 = FSL_PWM_CLK_FIX;
+		m1 = FSL_PWM_CLK_EXT;
+	} else {
+		m0 = FSL_PWM_CLK_EXT;
+		m1 = FSL_PWM_CLK_FIX;
+	}
+
+	fpc->counter_clk = cnt_clk[m0];
+	cycles = fsl_pwm_calculate_period_cycles(fpc, period_ns, m0);
+	if (cycles)
+		return cycles;
+
+	fpc->counter_clk = cnt_clk[m1];
+
+	return fsl_pwm_calculate_period_cycles(fpc, period_ns, m0);
+}
+
+static unsigned long fsl_pwm_calculate_duty(struct fsl_pwm_chip *fpc,
+					    unsigned long period_ns,
+					    unsigned long duty_ns)
+{
+	unsigned long long val, duty;
+
+	val = readl(fpc->base + FTM_MOD);
+	duty = duty_ns * (val + 1);
+	do_div(duty, period_ns);
+
+	return (unsigned long)duty;
+}
+
+static int fsl_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			  int duty_ns, int period_ns)
+{
+	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
+	u32 val, period, duty;
+
+	mutex_lock(&fpc->lock);
+
+	/*
+	 * The Freescale FTM controller supports only a single period for
+	 * all PWM channels, therefore incompatible changes need to be
+	 * refused.
+	 */
+	if (fpc->period_ns && fpc->period_ns != period_ns) {
+		dev_err(fpc->chip.dev,
+				"conflicting period requested for PWM %u\n",
+				pwm->hwpwm);
+		mutex_unlock(&fpc->lock);
+		return -EBUSY;
+	}
+
+	if (!fpc->period_ns && duty_ns) {
+		period = fsl_pwm_calculate_period(fpc, period_ns);
+		if (!period) {
+			dev_err(fpc->chip.dev, "failed to calculate period\n");
+			mutex_unlock(&fpc->lock);
+			return -EINVAL;
+		}
+
+		val = readl(fpc->base + FTM_SC);
+		val &= ~(FTM_SC_PS_MASK << FTM_SC_PS_SHIFT);
+		val |= fpc->clk_ps;
+		writel(val, fpc->base + FTM_SC);
+		writel(period - 1, fpc->base + FTM_MOD);
+
+		fpc->period_ns = period_ns;
+	}
+
+	mutex_unlock(&fpc->lock);
+
+	duty = fsl_pwm_calculate_duty(fpc, period_ns, duty_ns);
+
+	writel(FTM_CSC_MSB | FTM_CSC_ELSB, fpc->base + FTM_CSC(pwm->hwpwm));
+	writel(duty, fpc->base + FTM_CV(pwm->hwpwm));
+
+	return 0;
+}
+
+static int fsl_pwm_set_polarity(struct pwm_chip *chip,
+				struct pwm_device *pwm,
+				enum pwm_polarity polarity)
+{
+	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
+	u32 val;
+
+	val = readl(fpc->base + FTM_POL);
+
+	if (polarity == PWM_POLARITY_INVERSED)
+		val |= BIT(pwm->hwpwm);
+	else
+		val &= ~BIT(pwm->hwpwm);
+
+	writel(val, fpc->base + FTM_POL);
+
+	return 0;
+}
+
+static int fsl_counter_clock_enable(struct fsl_pwm_chip *fpc)
+{
+	u32 val;
+	int ret;
+
+	if (fpc->counter_clk_enable++)
+		return 0;
+
+	ret = clk_prepare_enable(fpc->counter_clk);
+	if (ret) {
+		fpc->counter_clk_enable--;
+		return ret;
+	}
+
+	ret = clk_prepare_enable(fpc->counter_clk_en);
+	if (ret) {
+		fpc->counter_clk_enable--;
+		return ret;
+	}
+
+	/* select counter clock source */
+	val = readl(fpc->base + FTM_SC);
+	val &= ~(FTM_SC_CLK_MASK << FTM_SC_CLK_SHIFT);
+	val |= fpc->counter_clk_select;
+	writel(val, fpc->base + FTM_SC);
+
+	return 0;
+}
+
+static int fsl_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
+	u32 val;
+	int ret;
+
+	val = readl(fpc->base + FTM_OUTMASK);
+	val &= ~BIT(pwm->hwpwm);
+	writel(val, fpc->base + FTM_OUTMASK);
+
+	mutex_lock(&fpc->lock);
+	ret = fsl_counter_clock_enable(fpc);
+	mutex_unlock(&fpc->lock);
+
+	return ret;
+}
+
+static void fsl_counter_clock_disable(struct fsl_pwm_chip *fpc)
+{
+	u32 val;
+
+	if (--fpc->counter_clk_enable)
+		return;
+
+	val = readl(fpc->base + FTM_SC);
+	val &= ~(FTM_SC_CLK_MASK << FTM_SC_CLK_SHIFT);
+	writel(val, fpc->base + FTM_SC);
+
+	clk_disable_unprepare(fpc->counter_clk_en);
+	clk_disable_unprepare(fpc->counter_clk);
+}
+
+static void fsl_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
+	u32 val;
+
+	val = readl(fpc->base + FTM_OUTMASK);
+	val |= BIT(pwm->hwpwm);
+	writel(val, fpc->base + FTM_OUTMASK);
+
+	mutex_lock(&fpc->lock);
+
+	fsl_counter_clock_disable(fpc);
+
+	val = readl(fpc->base + FTM_OUTMASK);
+
+	if ((val & 0xFF) == 0xFF) {
+		fpc->period_ns = 0;
+		fpc->counter_clk_en = NULL;
+	}
+
+	mutex_unlock(&fpc->lock);
+}
+
+static const struct pwm_ops fsl_pwm_ops = {
+	.request = fsl_pwm_request,
+	.free = fsl_pwm_free,
+	.config = fsl_pwm_config,
+	.set_polarity = fsl_pwm_set_polarity,
+	.enable = fsl_pwm_enable,
+	.disable = fsl_pwm_disable,
+	.owner = THIS_MODULE,
+};
+
+static int fsl_pwm_probe(struct platform_device *pdev)
+{
+	struct fsl_pwm_chip *fpc;
+	struct resource *res;
+	int ret;
+
+	fpc = devm_kzalloc(&pdev->dev, sizeof(*fpc), GFP_KERNEL);
+	if (!fpc)
+		return -ENOMEM;
+
+	mutex_init(&fpc->lock);
+
+	fpc->chip.dev = &pdev->dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	fpc->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(fpc->base))
+		return PTR_ERR(fpc->base);
+
+	fpc->sys_clk = devm_clk_get(&pdev->dev, "ftm_sys");
+	if (IS_ERR(fpc->sys_clk)) {
+		dev_err(&pdev->dev,
+				"failed to get \"ftm_sys\" clock\n");
+		return PTR_ERR(fpc->sys_clk);
+	}
+
+	ret = clk_prepare_enable(fpc->sys_clk);
+	if (ret)
+		return ret;
+
+	writel(0x00, fpc->base + FTM_CNTIN);
+	writel(0x00, fpc->base + FTM_OUTINIT);
+	writel(0xFF, fpc->base + FTM_OUTMASK);
+	clk_disable_unprepare(fpc->sys_clk);
+
+	fpc->chip.ops = &fsl_pwm_ops;
+	fpc->chip.of_xlate = of_pwm_xlate_with_flags;
+	fpc->chip.of_pwm_n_cells = 3;
+	fpc->chip.base = -1;
+	fpc->chip.npwm = 8;
+
+	ret = pwmchip_add(&fpc->chip);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to add PWM chip : %d\n", ret);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, fpc);
+
+	return 0;
+}
+
+static int fsl_pwm_remove(struct platform_device *pdev)
+{
+	struct fsl_pwm_chip *fpc = platform_get_drvdata(pdev);
+
+	return pwmchip_remove(&fpc->chip);
+}
+
+static const struct of_device_id fsl_pwm_dt_ids[] = {
+	{ .compatible = "fsl,vf610-ftm-pwm", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, fsl_pwm_dt_ids);
+
+static struct platform_driver fsl_pwm_driver = {
+	.driver = {
+		.name = "fsl-ftm-pwm",
+		.of_match_table = fsl_pwm_dt_ids,
+	},
+	.probe = fsl_pwm_probe,
+	.remove = fsl_pwm_remove,
+};
+module_platform_driver(fsl_pwm_driver);
+
+MODULE_DESCRIPTION("Freescale FlexTimer Module PWM Driver");
+MODULE_AUTHOR("Xiubo Li <Li.Xiubo@freescale.com>");
+MODULE_ALIAS("platform:fsl-ftm-pwm");
+MODULE_LICENSE("GPL");
-- 
1.8.4

Re: [PATCHv9 Resend 1/4] pwm: Add Freescale FTM PWM driver support

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 4609 bytes --]

Hi,

Sorry for taking so long to get back to you. Things have been quite busy
lately. A few more comments below, but we're getting there.

On Wed, Feb 19, 2014 at 04:38:54PM +0800, Xiubo Li wrote:
[...]
> diff --git a/drivers/pwm/pwm-fsl-ftm.c b/drivers/pwm/pwm-fsl-ftm.c
[...]
> +static unsigned long fsl_pwm_calculate_period(struct fsl_pwm_chip *fpc,
> +					      unsigned long period_ns)
> +{
> +	struct clk *cnt_clk[3];
> +	enum fsl_pwm_clk m0, m1;
> +	unsigned long fix_rate, ext_rate, cycles;
> +
> +	fpc->counter_clk = fpc->sys_clk;
> +	cycles = fsl_pwm_calculate_period_cycles(fpc, period_ns,
> +			FSL_PWM_CLK_SYS);
> +	if (cycles)
> +		return cycles;
> +
> +	cnt_clk[FSL_PWM_CLK_FIX] = devm_clk_get(fpc->chip.dev, "ftm_fix");
> +	if (IS_ERR(cnt_clk[FSL_PWM_CLK_FIX]))
> +		return PTR_ERR(cnt_clk[FSL_PWM_CLK_FIX]);
> +
> +	cnt_clk[FSL_PWM_CLK_EXT] = devm_clk_get(fpc->chip.dev, "ftm_ext");
> +	if (IS_ERR(cnt_clk[FSL_PWM_CLK_EXT]))
> +		return PTR_ERR(cnt_clk[FSL_PWM_CLK_EXT]);
> +
> +	fpc->counter_clk_en = devm_clk_get(fpc->chip.dev, "ftm_cnt_clk_en");
> +	if (IS_ERR(fpc->counter_clk_en))
> +		return PTR_ERR(fpc->counter_clk_en);

You shouldn't do this. You're obtaining a reference to each of these
clocks whenever pwm_config() is called. And devres will only clean those
up after the driver is unbound. Can't you simply keep a reference to
these within struct fsl_pwm_chip?

> +static int fsl_counter_clock_enable(struct fsl_pwm_chip *fpc)
> +{
> +	u32 val;
> +	int ret;
> +
> +	if (fpc->counter_clk_enable++)

This function is always called with the fpc->lock held, so you could
make this much easier by incrementing the .counter_clk_enable field only
at the very end of the function. That way...

> +		return 0;
> +
> +	ret = clk_prepare_enable(fpc->counter_clk);
> +	if (ret) {
> +		fpc->counter_clk_enable--;

... this won't be necessary...

> +		return ret;
> +	}
> +
> +	ret = clk_prepare_enable(fpc->counter_clk_en);
> +	if (ret) {
> +		fpc->counter_clk_enable--;

... and neither will this.

> +static int fsl_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
> +	u32 val;
> +	int ret;
> +
> +	val = readl(fpc->base + FTM_OUTMASK);
> +	val &= ~BIT(pwm->hwpwm);
> +	writel(val, fpc->base + FTM_OUTMASK);
> +
> +	mutex_lock(&fpc->lock);

I think you want to extend the lock to cover the FTM_OUTMASK register
access as well because there could be a race between pwm_enable() and
pwm_disable().

> +	ret = fsl_counter_clock_enable(fpc);
> +	mutex_unlock(&fpc->lock);
> +
> +	return ret;
> +}

Can this function be moved somewhere else so fsl_counter_clock_enable()
and fsl_counter_clock_disable() are grouped together?

> +static void fsl_counter_clock_disable(struct fsl_pwm_chip *fpc)
> +{
> +	u32 val;
> +
> +	if (--fpc->counter_clk_enable)
> +		return;

This is going to break. Consider the case where you call pwm_disable()
on a PWM device and fpc->counter_clk_enable == 1. In that case, this
will decrement counter_clk_enable to 0 and proceed with the remainder of
this function.

Now you call pwm_disable() again. The above will decrement again and
cause fpc->counter_clk_enable to wrap around to UINT_MAX.

So I think a more correct implementation would be:

	/*
	 * already disabled, do nothing (perhaps output warning message
	 * to catch unbalanced calls? )
	 */
	if (fpc->counter_clk_enable == 0)
		return;

	/* there are still users, so can't disable yet */
	if (--fpc->counter_clk_enable > 0)
		return;

	/* no users left, disable clock */

> +static void fsl_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
> +	u32 val;
> +
> +	val = readl(fpc->base + FTM_OUTMASK);
> +	val |= BIT(pwm->hwpwm);
> +	writel(val, fpc->base + FTM_OUTMASK);
> +
> +	mutex_lock(&fpc->lock);

This lock should also include the access to FTM_OUTMASK above.

> +static int fsl_pwm_probe(struct platform_device *pdev)
> +{
[...]
> +	fpc->sys_clk = devm_clk_get(&pdev->dev, "ftm_sys");
> +	if (IS_ERR(fpc->sys_clk)) {
> +		dev_err(&pdev->dev,
> +				"failed to get \"ftm_sys\" clock\n");

The above easily fits on a single line, no need for the wrapping.

> +		return PTR_ERR(fpc->sys_clk);
> +	}
> +
> +	ret = clk_prepare_enable(fpc->sys_clk);
> +	if (ret)
> +		return ret;
> +
> +	writel(0x00, fpc->base + FTM_CNTIN);
> +	writel(0x00, fpc->base + FTM_OUTINIT);
> +	writel(0xFF, fpc->base + FTM_OUTMASK);
> +	clk_disable_unprepare(fpc->sys_clk);

This looks out of place somehow, perhaps it should be moved off into a
separate function? fsl_pwm_init() perhaps.

Thierry

[-- Attachment #2: Type: application/pgp-signature, Size: 836 bytes --]

RE: [PATCHv9 Resend 1/4] pwm: Add Freescale FTM PWM driver support

[Li.Xiubo]

Hi Thierry,

Thanks very much, I will fix them all.

:)

--
Best Regards,
Xiubo

> Sorry for taking so long to get back to you. Things have been quite busy
> lately. A few more comments below, but we're getting there.
> 
> On Wed, Feb 19, 2014 at 04:38:54PM +0800, Xiubo Li wrote:
> [...]
> > diff --git a/drivers/pwm/pwm-fsl-ftm.c b/drivers/pwm/pwm-fsl-ftm.c
> [...]
> > +static unsigned long fsl_pwm_calculate_period(struct fsl_pwm_chip *fpc,
> > +					      unsigned long period_ns)
> > +{
> > +	struct clk *cnt_clk[3];
> > +	enum fsl_pwm_clk m0, m1;
> > +	unsigned long fix_rate, ext_rate, cycles;
> > +
> > +	fpc->counter_clk = fpc->sys_clk;
> > +	cycles = fsl_pwm_calculate_period_cycles(fpc, period_ns,
> > +			FSL_PWM_CLK_SYS);
> > +	if (cycles)
> > +		return cycles;
> > +
> > +	cnt_clk[FSL_PWM_CLK_FIX] = devm_clk_get(fpc->chip.dev, "ftm_fix");
> > +	if (IS_ERR(cnt_clk[FSL_PWM_CLK_FIX]))
> > +		return PTR_ERR(cnt_clk[FSL_PWM_CLK_FIX]);
> > +
> > +	cnt_clk[FSL_PWM_CLK_EXT] = devm_clk_get(fpc->chip.dev, "ftm_ext");
> > +	if (IS_ERR(cnt_clk[FSL_PWM_CLK_EXT]))
> > +		return PTR_ERR(cnt_clk[FSL_PWM_CLK_EXT]);
> > +
> > +	fpc->counter_clk_en = devm_clk_get(fpc->chip.dev, "ftm_cnt_clk_en");
> > +	if (IS_ERR(fpc->counter_clk_en))
> > +		return PTR_ERR(fpc->counter_clk_en);
> 
> You shouldn't do this. You're obtaining a reference to each of these
> clocks whenever pwm_config() is called. And devres will only clean those
> up after the driver is unbound. Can't you simply keep a reference to
> these within struct fsl_pwm_chip?
> 
> > +static int fsl_counter_clock_enable(struct fsl_pwm_chip *fpc)
> > +{
> > +	u32 val;
> > +	int ret;
> > +
> > +	if (fpc->counter_clk_enable++)
> 
> This function is always called with the fpc->lock held, so you could
> make this much easier by incrementing the .counter_clk_enable field only
> at the very end of the function. That way...
> 
> > +		return 0;
> > +
> > +	ret = clk_prepare_enable(fpc->counter_clk);
> > +	if (ret) {
> > +		fpc->counter_clk_enable--;
> 
> ... this won't be necessary...
> 
> > +		return ret;
> > +	}
> > +
> > +	ret = clk_prepare_enable(fpc->counter_clk_en);
> > +	if (ret) {
> > +		fpc->counter_clk_enable--;
> 
> ... and neither will this.
> 
> > +static int fsl_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> > +{
> > +	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
> > +	u32 val;
> > +	int ret;
> > +
> > +	val = readl(fpc->base + FTM_OUTMASK);
> > +	val &= ~BIT(pwm->hwpwm);
> > +	writel(val, fpc->base + FTM_OUTMASK);
> > +
> > +	mutex_lock(&fpc->lock);
> 
> I think you want to extend the lock to cover the FTM_OUTMASK register
> access as well because there could be a race between pwm_enable() and
> pwm_disable().
> 
> > +	ret = fsl_counter_clock_enable(fpc);
> > +	mutex_unlock(&fpc->lock);
> > +
> > +	return ret;
> > +}
> 
> Can this function be moved somewhere else so fsl_counter_clock_enable()
> and fsl_counter_clock_disable() are grouped together?
> 
> > +static void fsl_counter_clock_disable(struct fsl_pwm_chip *fpc)
> > +{
> > +	u32 val;
> > +
> > +	if (--fpc->counter_clk_enable)
> > +		return;
> 
> This is going to break. Consider the case where you call pwm_disable()
> on a PWM device and fpc->counter_clk_enable == 1. In that case, this
> will decrement counter_clk_enable to 0 and proceed with the remainder of
> this function.
> 
> Now you call pwm_disable() again. The above will decrement again and
> cause fpc->counter_clk_enable to wrap around to UINT_MAX.
> 
> So I think a more correct implementation would be:
> 
> 	/*
> 	 * already disabled, do nothing (perhaps output warning message
> 	 * to catch unbalanced calls? )
> 	 */
> 	if (fpc->counter_clk_enable == 0)
> 		return;
> 
> 	/* there are still users, so can't disable yet */
> 	if (--fpc->counter_clk_enable > 0)
> 		return;
> 
> 	/* no users left, disable clock */
> 
> > +static void fsl_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> > +{
> > +	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
> > +	u32 val;
> > +
> > +	val = readl(fpc->base + FTM_OUTMASK);
> > +	val |= BIT(pwm->hwpwm);
> > +	writel(val, fpc->base + FTM_OUTMASK);
> > +
> > +	mutex_lock(&fpc->lock);
> 
> This lock should also include the access to FTM_OUTMASK above.
> 
> > +static int fsl_pwm_probe(struct platform_device *pdev)
> > +{
> [...]
> > +	fpc->sys_clk = devm_clk_get(&pdev->dev, "ftm_sys");
> > +	if (IS_ERR(fpc->sys_clk)) {
> > +		dev_err(&pdev->dev,
> > +				"failed to get \"ftm_sys\" clock\n");
> 
> The above easily fits on a single line, no need for the wrapping.
> 
> > +		return PTR_ERR(fpc->sys_clk);
> > +	}
> > +
> > +	ret = clk_prepare_enable(fpc->sys_clk);
> > +	if (ret)
> > +		return ret;
> > +
> > +	writel(0x00, fpc->base + FTM_CNTIN);
> > +	writel(0x00, fpc->base + FTM_OUTINIT);
> > +	writel(0xFF, fpc->base + FTM_OUTMASK);
> > +	clk_disable_unprepare(fpc->sys_clk);
> 
> This looks out of place somehow, perhaps it should be moved off into a
> separate function? fsl_pwm_init() perhaps.
> 
> Thierry

[PATCHv9 Resend 2/4] ARM: dts: vf610: Add Freescale FTM PWM node.

[Xiubo Li]

This adds devicetree node for VF610, and there are 8 channels
supported.

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Yuan Yao <yao.yuan@freescale.com>
---
 arch/arm/boot/dts/vf610.dtsi | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm/boot/dts/vf610.dtsi b/arch/arm/boot/dts/vf610.dtsi
index d31ce1b..6cce861 100644
--- a/arch/arm/boot/dts/vf610.dtsi
+++ b/arch/arm/boot/dts/vf610.dtsi
@@ -152,6 +152,19 @@
 				clock-names = "pit";
 			};
 
+			pwm0: pwm@40038000 {
+				compatible = "fsl,vf610-ftm-pwm";
+				#pwm-cells = <3>;
+				reg = <0x40038000 0x1000>;
+				clock-names = "ftm_sys", "ftm_ext",
+					      "ftm_fix", "ftm_cnt_clk_en";
+				clocks = <&clks VF610_CLK_FTM0>,
+					<&clks VF610_CLK_FTM0_EXT_SEL>,
+					<&clks VF610_CLK_FTM0_FIX_SEL>,
+					<&clks VF610_CLK_FTM0_EXT_FIX_EN>;
+				status = "disabled";
+			};
+
 			wdog@4003e000 {
 				compatible = "fsl,vf610-wdt", "fsl,imx21-wdt";
 				reg = <0x4003e000 0x1000>;
-- 
1.8.4

[PATCHv9 Resend 3/4] ARM: dts: vf610-twr: Enables FTM PWM device.

[Xiubo Li]

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Yuan Yao <yao.yuan@freescale.com>
---
 arch/arm/boot/dts/vf610-twr.dts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/boot/dts/vf610-twr.dts b/arch/arm/boot/dts/vf610-twr.dts
index c3a3237..d5c6a39 100644
--- a/arch/arm/boot/dts/vf610-twr.dts
+++ b/arch/arm/boot/dts/vf610-twr.dts
@@ -100,6 +100,12 @@
 	status = "okay";
 };
 
+&pwm0 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_pwm0_1>;
+	status = "okay";
+};
+
 &uart1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_uart1_1>;
-- 
1.8.4

[PATCHv9 Resend 4/4] Documentation: Add device tree bindings for Freescale FTM PWM.

[Xiubo Li]

This adds the binding documentation for Freescale FlexTimer Module
(FTM) PWM driver under Documentation/devicetree/bindings/pwm/.

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Yuan Yao <yao.yuan@freescale.com>
Acked-by: Kumar Gala <galak@codeaurora.org>
---
 .../devicetree/bindings/pwm/pwm-fsl-ftm.txt        | 34 ++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt

diff --git a/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt b/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
new file mode 100644
index 0000000..1c310df
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
@@ -0,0 +1,34 @@
+Freescale FlexTimer Module (FTM) PWM controller
+
+Required properties:
+- compatible: Should be "fsl,vf610-ftm-pwm".
+- reg: Physical base address and length of the controller's registers
+- #pwm-cells: Should be 3. See pwm.txt in this directory for a description of
+  the cells format.
+- clock-names : Should include the following module clock source entries:
+    "ftm_sys" (module clock, also can be used as counter clock),
+    "ftm_ext" (external counter clock),
+    "ftm_fix" (fixed counter clock),
+    "ftm_cnt_clk_en" (external and fixed counter clock enable/disable).
+- clocks : Must contain a clock specifier for each entry in clock-names,
+  See clock/clock-bindings.txt for details of the property values.
+- pinctrl-names: Must contain a "default" entry.
+- pinctrl-NNN: One property must exist for each entry in pinctrl-names.
+  See pinctrl/pinctrl-bindings.txt for details of the property values.
+
+
+Example:
+
+pwm0: pwm@40038000 {
+		compatible = "fsl,vf610-ftm-pwm";
+		reg = <0x40038000 0x1000>;
+		#pwm-cells = <3>;
+		clock-names = "ftm_sys", "ftm_ext",
+				"ftm_fix", "ftm_cnt_clk_en";
+		clocks = <&clks VF610_CLK_FTM0>,
+			<&clks VF610_CLK_FTM0_EXT_SEL>,
+			<&clks VF610_CLK_FTM0_FIX_SEL>,
+			<&clks VF610_CLK_FTM0_EXT_FIX_EN>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_pwm0_1>;
+};
-- 
1.8.4

Re: [PATCHv9 Resend 4/4] Documentation: Add device tree bindings for Freescale FTM PWM.

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 939 bytes --]

On Wed, Feb 19, 2014 at 04:38:57PM +0800, Xiubo Li wrote:
> This adds the binding documentation for Freescale FlexTimer Module
> (FTM) PWM driver under Documentation/devicetree/bindings/pwm/.
> 
> Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
> Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
> Reviewed-by: Yuan Yao <yao.yuan@freescale.com>
> Acked-by: Kumar Gala <galak@codeaurora.org>
> ---
>  .../devicetree/bindings/pwm/pwm-fsl-ftm.txt        | 34 ++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt b/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
[...]
> +- clocks : Must contain a clock specifier for each entry in clock-names,

Nit: A slightly more correct way to say this would be: "Must contain a
phandle and clock specifier...".

Thierry

[-- Attachment #2: Type: application/pgp-signature, Size: 836 bytes --]

RE: [PATCHv9 Resend 4/4] Documentation: Add device tree bindings for Freescale FTM PWM.

[Li.Xiubo]

> >  create mode 100644 Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
> >
> > diff --git a/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
> b/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
> [...]
> > +- clocks : Must contain a clock specifier for each entry in clock-names,
> 
> Nit: A slightly more correct way to say this would be: "Must contain a
> phandle and clock specifier...".
> 

Yes, I will fix this.

Thanks very much,

--
Best Regards,
Xiubo

RE: [PATCHv9 Resend 0/4] Add Freescale FTM PWM driver

[Li.Xiubo]

Thierry, Ping ? :)



> -----Original Message-----
> From: Xiubo Li [mailto:Li.Xiubo@freescale.com]
> Sent: Wednesday, February 19, 2014 4:39 PM
> To: thierry.reding@gmail.com; linux-pwm@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org; Xiubo Li-B47053
> Subject: [PATCHv9 Resend 0/4] Add Freescale FTM PWM driver
> 
> Resend this patch series, just adding the missing and new Reviewed-by and
> Acked-by infomation of this patch series.
> 
> 
> Xiubo Li (4):
>   pwm: Add Freescale FTM PWM driver support
>   ARM: dts: vf610: Add Freescale FTM PWM node.
>   ARM: dts: vf610-twr: Enables FTM PWM device.
>   Documentation: Add device tree bindings for Freescale FTM PWM.
> 
>  .../devicetree/bindings/pwm/pwm-fsl-ftm.txt        |  34 ++
>  arch/arm/boot/dts/vf610-twr.dts                    |   6 +
>  arch/arm/boot/dts/vf610.dtsi                       |  13 +
>  drivers/pwm/Kconfig                                |  10 +
>  drivers/pwm/Makefile                               |   1 +
>  drivers/pwm/pwm-fsl-ftm.c                          | 479
> +++++++++++++++++++++
>  6 files changed, 543 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
>  create mode 100644 drivers/pwm/pwm-fsl-ftm.c
> 
> --
> 1.8.4
>