[V4] pwm: lpc32xx - Add a driver for the motor PWM

Message ID 1410363822-22151-1-git-send-email-alban.bedel@avionic-design.de
State New
Headers show

Commit Message

Alban Bedel Sept. 10, 2014, 3:43 p.m.
The LPC32xx motor PWMs have 3 channels that each drives a pair of
pins A and B, with B = !A. The polarity configuration is from the
point of view of pin A, so when using pin B the polarity is inverted.

Signed-off-by: Alban Bedel <alban.bedel@avionic-design.de>
---
V4: * Fixed the Kconfig dependencies
    * Replaced __raw_writel() with writel()
    * Implemented .set_polarity()
    * Replaced the linux,polarity property with flags in the
      pwm-cell using the common of_pwm_xlate_with_flags()
    * Tried to clarify the device description in the DT binding
    * Added optional clock properties to the binding definition
    * Fixed the number of pwm cells in the LPC32xx DTSi
V3: * Updated to current mainline API
    * Fixed LPC32xx vs. LPC32XX
    * Various coding style fix
V2: * Splitted the DTS to its own patch
---
 .../devicetree/bindings/pwm/lpc32xx-motor-pwm.txt  |  30 +++
 arch/arm/boot/dts/lpc32xx.dtsi                     |   2 +-
 drivers/pwm/Kconfig                                |  11 ++
 drivers/pwm/Makefile                               |   1 +
 drivers/pwm/pwm-lpc32xx-motor.c                    | 215 +++++++++++++++++++++
 5 files changed, 258 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/devicetree/bindings/pwm/lpc32xx-motor-pwm.txt
 create mode 100644 drivers/pwm/pwm-lpc32xx-motor.c

Comments

Arnd Bergmann Sept. 10, 2014, 3:51 p.m. | #1
On Wednesday 10 September 2014 17:43:42 Alban Bedel wrote:
> +- #pwm-cells: should be 3. See pwm.txt in this directory for a description of
> +  the cells format. The only third cell flag supported by this binding is
> +  PWM_POLARITY_INVERTED.

If you don't have multiple pwm outputs or programmable period, I would say it
should use #pwm-cells=<1> and only pass the polarity.

	Arnd
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Alban Bedel Sept. 10, 2014, 3:59 p.m. | #2
On Wed, 10 Sep 2014 17:51:36 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> On Wednesday 10 September 2014 17:43:42 Alban Bedel wrote:
> > +- #pwm-cells: should be 3. See pwm.txt in this directory for a description of
> > +  the cells format. The only third cell flag supported by this binding is
> > +  PWM_POLARITY_INVERTED.
> 
> If you don't have multiple pwm outputs or programmable period, I would say it
> should use #pwm-cells=<1> and only pass the polarity.

There is 3 channel, so 3 PWM from the API POV, and the period is
independently programmable for each one.

Alban
Arnd Bergmann Sept. 10, 2014, 4:28 p.m. | #3
On Wednesday 10 September 2014 17:59:41 Alban Bedel wrote:
> On Wed, 10 Sep 2014 17:51:36 +0200
> Arnd Bergmann <arnd@arndb.de> wrote:
> 
> > On Wednesday 10 September 2014 17:43:42 Alban Bedel wrote:
> > > +- #pwm-cells: should be 3. See pwm.txt in this directory for a description of
> > > +  the cells format. The only third cell flag supported by this binding is
> > > +  PWM_POLARITY_INVERTED.
> > 
> > If you don't have multiple pwm outputs or programmable period, I would say it
> > should use #pwm-cells=<1> and only pass the polarity.
> 
> There is 3 channel, so 3 PWM from the API POV, and the period is
> independently programmable for each one.

Then you should put the channel number into the first cell and the period
length into the second cell, as the pwm.txt document says.

	Arnd
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Alban Bedel Sept. 11, 2014, 8:36 a.m. | #4
On Wed, 10 Sep 2014 18:28:39 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> On Wednesday 10 September 2014 17:59:41 Alban Bedel wrote:
> > On Wed, 10 Sep 2014 17:51:36 +0200
> > Arnd Bergmann <arnd@arndb.de> wrote:
> > 
> > > On Wednesday 10 September 2014 17:43:42 Alban Bedel wrote:
> > > > +- #pwm-cells: should be 3. See pwm.txt in this directory for a description of
> > > > +  the cells format. The only third cell flag supported by this binding is
> > > > +  PWM_POLARITY_INVERTED.
> > > 
> > > If you don't have multiple pwm outputs or programmable period, I would say it
> > > should use #pwm-cells=<1> and only pass the polarity.
> > 
> > There is 3 channel, so 3 PWM from the API POV, and the period is
> > independently programmable for each one.
> 
> Then you should put the channel number into the first cell and the period
> length into the second cell, as the pwm.txt document says.

That's what is implemented in this patch, by using
of_pwm_xlate_with_flags() for the .of_xlate callback.

Alban
Arnd Bergmann Sept. 11, 2014, 9:39 a.m. | #5
On Thursday 11 September 2014 10:36:21 Alban Bedel wrote:
> On Wed, 10 Sep 2014 18:28:39 +0200
> Arnd Bergmann <arnd@arndb.de> wrote:
> 
> > On Wednesday 10 September 2014 17:59:41 Alban Bedel wrote:
> > > On Wed, 10 Sep 2014 17:51:36 +0200
> > > Arnd Bergmann <arnd@arndb.de> wrote:
> > > 
> > > > On Wednesday 10 September 2014 17:43:42 Alban Bedel wrote:
> > > > > +- #pwm-cells: should be 3. See pwm.txt in this directory for a description of
> > > > > +  the cells format. The only third cell flag supported by this binding is
> > > > > +  PWM_POLARITY_INVERTED.
> > > > 
> > > > If you don't have multiple pwm outputs or programmable period, I would say it
> > > > should use #pwm-cells=<1> and only pass the polarity.
> > > 
> > > There is 3 channel, so 3 PWM from the API POV, and the period is
> > > independently programmable for each one.
> > 
> > Then you should put the channel number into the first cell and the period
> > length into the second cell, as the pwm.txt document says.
> 
> That's what is implemented in this patch, by using
> of_pwm_xlate_with_flags() for the .of_xlate callback.
> 

Ah, my mistake. I misread the sentence in the binding for meaning that
you only support the third cell. It's all good then.

	Arnd
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Patch

diff --git a/Documentation/devicetree/bindings/pwm/lpc32xx-motor-pwm.txt b/Documentation/devicetree/bindings/pwm/lpc32xx-motor-pwm.txt
new file mode 100644
index 0000000..76a086d
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/lpc32xx-motor-pwm.txt
@@ -0,0 +1,30 @@ 
+LPC32xx Motor PWM controller
+
+The LPC32xx motor PWMs have 3 channels that each drives a pair of
+pins A and B, with B = !A. The polarity configuration is from the
+point of view of pin A, so when using pin B the polarity is inverted.
+
+Required properties:
+- compatible: should be "nxp,lpc3220-motor-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. The only third cell flag supported by this binding is
+  PWM_POLARITY_INVERTED.
+
+Optional properties:
+- clock-names: Set to "mpwm"
+- clocks: phandle of the clock used by the PWM module.
+  See ../clocks/clock-bindings.txt for details.
+
+Note: The clock properties are currently optional because the LPC32xx
+  architecture doesn't have a DT-aware clocksource driver yet.
+
+Examples:
+
+mpwm@400e8000 {
+	compatible = "nxp,lpc3220-motor-pwm";
+	reg = <0x400E8000 0x78>;
+	#pwm-cells = <3>;
+	clock-names = "mpwm";
+	clocks = <&clk_mpwm>;
+};
diff --git a/arch/arm/boot/dts/lpc32xx.dtsi b/arch/arm/boot/dts/lpc32xx.dtsi
index 3abebb7..bde722e 100644
--- a/arch/arm/boot/dts/lpc32xx.dtsi
+++ b/arch/arm/boot/dts/lpc32xx.dtsi
@@ -190,7 +190,7 @@ 
 				compatible = "nxp,lpc3220-motor-pwm";
 				reg = <0x400E8000 0x78>;
 				status = "disabled";
-				#pwm-cells = <2>;
+				#pwm-cells = <3>; /* pwm, period, flags */
 			};
 
 			i2cusb: i2c@31020300 {
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index b800783..a2f5f98 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -147,6 +147,17 @@  config PWM_LPC32XX
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-lpc32xx.
 
+config PWM_LPC32XX_MOTOR
+	tristate "LPC32xx Motor PWM support"
+	depends on ARCH_LPC32XX || COMPILE_TEST
+	depends on CLKDEV_LOOKUP
+	help
+	  Generic PWM framework driver for LPC32xx motor PWM. The LPC32xx SOC
+	  has one motor PWM controllers.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-lpc32xx-motor.
+
 config PWM_LPSS
 	tristate "Intel LPSS PWM support"
 	depends on ACPI
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index f8c577d..3eb5dd9 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -12,6 +12,7 @@  obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
 obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
 obj-$(CONFIG_PWM_LP3943)	+= pwm-lp3943.o
 obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
+obj-$(CONFIG_PWM_LPC32XX_MOTOR)	+= pwm-lpc32xx-motor.o
 obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
 obj-$(CONFIG_PWM_MXS)		+= pwm-mxs.o
 obj-$(CONFIG_PWM_PCA9685)	+= pwm-pca9685.o
diff --git a/drivers/pwm/pwm-lpc32xx-motor.c b/drivers/pwm/pwm-lpc32xx-motor.c
new file mode 100644
index 0000000..866adb6
--- /dev/null
+++ b/drivers/pwm/pwm-lpc32xx-motor.c
@@ -0,0 +1,215 @@ 
+/*
+ * Copyright 2012-2014 Alban Bedel <alban.bedel@avionic-design.de>
+ *
+ * Based on pwm-lpc32xx.c from Alexandre Pereira da Silva
+ * <aletes.xgr@gmail.com>
+ *
+ * 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; version 2.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+struct lpc32xx_motor_pwm_chip {
+	struct pwm_chip chip;
+	struct clk *clk;
+	unsigned int pins;
+	void __iomem *base;
+};
+
+#define to_motor_pwm_chip(_chip) \
+	container_of(_chip, struct lpc32xx_motor_pwm_chip, chip)
+
+/* Register mapping for MCPWM modules */
+#define LPC32XX_MCPWM_MCCON		0x00
+#define LPC32XX_MCPWM_MCCON_SET		0x04
+#define LPC32XX_MCPWM_MCCON_CLR		0x08
+#define LPC32XX_MCPWM_MCCAPCON		0x0C
+#define LPC32XX_MCPWM_MCCAPCON_SET	0x10
+#define LPC32XX_MCPWM_MCCAPCON_CLR	0x14
+#define LPC32XX_MCPWM_MCLIM0		0x24
+#define LPC32XX_MCPWM_MCLIM1		0x28
+#define LPC32XX_MCPWM_MCLIM2		0x2C
+#define LPC32XX_MCPWM_MCMAT0		0x30
+#define LPC32XX_MCPWM_MCMAT1		0x34
+#define LPC32XX_MCPWM_MCMAT2		0x38
+#define LPC32XX_MCPWM_MCINTEN_CLR	0x58
+
+#define LPC32XX_MCPWM_COUNT		3
+
+#define PWM_EN_MASK(pwm)	BIT(0 + (pwm)->hwpwm * 8)
+#define PWM_POL_MASK(pwm)	BIT(2 + (pwm)->hwpwm * 8)
+#define MCLIM_REG_OFFSET(pwm)	(LPC32XX_MCPWM_MCLIM0 + (pwm)->hwpwm * 4)
+#define MCMAT_REG_OFFSET(pwm)	(LPC32XX_MCPWM_MCMAT0 + (pwm)->hwpwm * 4)
+
+static int lpc32xx_motor_pwm_config(struct pwm_chip *chip,
+				    struct pwm_device *pwm,
+				    int duty_ns, int period_ns)
+{
+	struct lpc32xx_motor_pwm_chip *lpc32xx = to_motor_pwm_chip(chip);
+	u64 rate, period, duty;
+	int err;
+
+	/* The clock is needed to access the registers */
+	err = clk_enable(lpc32xx->clk);
+	if (err)
+		return err;
+
+	/* Calculate period */
+	rate = clk_get_rate(lpc32xx->clk);
+	period  = (u64)period_ns * rate;
+	duty = (u64)duty_ns * rate;
+	do_div(period,  1000000000);
+	do_div(duty, 1000000000);
+
+	/* Write to limit register -> period */
+	writel(period, lpc32xx->base + MCLIM_REG_OFFSET(pwm));
+
+	/* Write to match register -> duty */
+	writel(period - duty, lpc32xx->base + MCMAT_REG_OFFSET(pwm));
+
+	/* Disable the clock now that we are done */
+	clk_disable(lpc32xx->clk);
+	return 0;
+}
+
+static int lpc32xx_motor_pwm_set_polarity(struct pwm_chip *chip,
+					  struct pwm_device *pwm,
+					  enum pwm_polarity polarity)
+{
+	struct lpc32xx_motor_pwm_chip *lpc32xx = to_motor_pwm_chip(chip);
+	int err = 0;
+
+	/* The clock is needed to access the registers */
+	err = clk_enable(lpc32xx->clk);
+	if (err)
+		return err;
+
+	if (polarity == PWM_POLARITY_NORMAL)
+		writel(PWM_POL_MASK(pwm),
+		       lpc32xx->base + LPC32XX_MCPWM_MCCON_CLR);
+	else
+		writel(PWM_POL_MASK(pwm),
+		       lpc32xx->base + LPC32XX_MCPWM_MCCON_SET);
+
+	/* Disable the clock now that we are done */
+	clk_disable(lpc32xx->clk);
+	return 0;
+}
+
+static int lpc32xx_motor_pwm_enable(struct pwm_chip *chip,
+				    struct pwm_device *pwm)
+{
+	struct lpc32xx_motor_pwm_chip *lpc32xx = to_motor_pwm_chip(chip);
+	int err;
+
+	err = clk_enable(lpc32xx->clk);
+	if (err)
+		return err;
+
+	writel(PWM_EN_MASK(pwm), lpc32xx->base + LPC32XX_MCPWM_MCCON_SET);
+
+	return 0;
+}
+
+static void lpc32xx_motor_pwm_disable(struct pwm_chip *chip,
+				      struct pwm_device *pwm)
+{
+	struct lpc32xx_motor_pwm_chip *lpc32xx = to_motor_pwm_chip(chip);
+
+	writel(PWM_EN_MASK(pwm), lpc32xx->base + LPC32XX_MCPWM_MCCON_CLR);
+
+	clk_disable(lpc32xx->clk);
+}
+
+static const struct pwm_ops lpc32xx_motor_pwm_ops = {
+	.config = lpc32xx_motor_pwm_config,
+	.set_polarity = lpc32xx_motor_pwm_set_polarity,
+	.enable = lpc32xx_motor_pwm_enable,
+	.disable = lpc32xx_motor_pwm_disable,
+	.owner = THIS_MODULE,
+};
+
+static int lpc32xx_motor_pwm_probe(struct platform_device *pdev)
+{
+	struct lpc32xx_motor_pwm_chip *lpc32xx;
+	struct resource *res;
+	int ret;
+
+	lpc32xx = devm_kzalloc(&pdev->dev, sizeof(*lpc32xx), GFP_KERNEL);
+	if (!lpc32xx)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	lpc32xx->base = devm_ioremap_resource(&pdev->dev, res);
+	if (!lpc32xx->base)
+		return -EADDRNOTAVAIL;
+
+	lpc32xx->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(lpc32xx->clk))
+		return PTR_ERR(lpc32xx->clk);
+
+	lpc32xx->chip.dev = &pdev->dev;
+	lpc32xx->chip.ops = &lpc32xx_motor_pwm_ops;
+	lpc32xx->chip.of_xlate = of_pwm_xlate_with_flags;
+	lpc32xx->chip.of_pwm_n_cells = 3;
+	lpc32xx->chip.npwm = LPC32XX_MCPWM_COUNT;
+	lpc32xx->chip.base = -1;
+
+	ret = pwmchip_add(&lpc32xx->chip);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, lpc32xx);
+
+	return 0;
+}
+
+static int lpc32xx_motor_pwm_remove(struct platform_device *pdev)
+{
+	struct lpc32xx_motor_pwm_chip *lpc32xx = platform_get_drvdata(pdev);
+	int i;
+
+	for (i = 0; i < lpc32xx->chip.npwm; i++)
+		pwm_disable(&lpc32xx->chip.pwms[i]);
+
+	return pwmchip_remove(&lpc32xx->chip);
+}
+
+static const struct of_device_id lpc32xx_motor_pwm_dt_ids[] = {
+	{ .compatible = "nxp,lpc3220-motor-pwm", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, lpc32xx_motor_pwm_dt_ids);
+
+static struct platform_driver lpc32xx_motor_pwm_driver = {
+	.driver = {
+		.name = "lpc32xx-motor-pwm",
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(lpc32xx_motor_pwm_dt_ids),
+	},
+	.probe = lpc32xx_motor_pwm_probe,
+	.remove = lpc32xx_motor_pwm_remove,
+};
+module_platform_driver(lpc32xx_motor_pwm_driver);
+
+MODULE_ALIAS("platform:lpc32xx-motor-pwm");
+MODULE_AUTHOR("Alban Bedel <alban.bedel@avionic-design.de>");
+MODULE_DESCRIPTION("LPC32xx Motor PWM Driver");
+MODULE_LICENSE("GPL v2");