drivers/pwm: add PXA pulse width modulator controller

Add PXA embedded pulse width modulator support. The PWM can
generate signals from 49.6kHz to 1.625MHz.
The driver is for pxa2xx family. The pxa3xx was not handled yet.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-pxa/Makefile

@@ -1,6 +1,7 @@
 obj-y += clocksource.o
 obj-y += common.o
 obj-y += gpio.o
+obj-y += devices.o
 
 obj-$(CONFIG_ARCH_PXA2XX) += mfp-pxa2xx.o
 obj-$(CONFIG_ARCH_PXA27X) += speed-pxa27x.o

arch/arm/mach-pxa/devices.c

@@ -47,3 +47,8 @@ struct device_d *pxa_add_mmc(void *base, int id, void *pdata)
 {
 	return pxa_add_device("pxa-mmc", id, base, 0x1000, pdata);
 }
+
+struct device_d *pxa_add_pwm(void *base, int id)
+{
+	return pxa_add_device("pxa_pwm", id, base, 0x10, NULL);
+}

arch/arm/mach-pxa/include/mach/clock.h

@@ -14,5 +14,6 @@
 unsigned long pxa_get_uartclk(void);
 unsigned long pxa_get_mmcclk(void);
 unsigned long pxa_get_lcdclk(void);
+unsigned long pxa_get_pwmclk(void);
 
 #endif	/* !__MACH_CLOCK_H */

arch/arm/mach-pxa/include/mach/devices.h

@@ -23,4 +23,4 @@ struct device_d *pxa_add_i2c(void *base, int id,
 struct device_d *pxa_add_uart(void *base, int id);
 struct device_d *pxa_add_fb(void *base, struct pxafb_platform_data *pdata);
 struct device_d *pxa_add_mmc(void *base, int id, void *pdata);
-
+struct device_d *pxa_add_pwm(void *base, int id);

arch/arm/mach-pxa/include/mach/regs-pwm.h

@@ -0,0 +1,20 @@
+/*
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+#ifndef __ASM_MACH_REGS_PWM_H
+#define __ASM_MACH_REGS_PWM_H
+
+#include <mach/hardware.h>
+
+/*
+ * Pulse modulator registers
+ */
+#define PWM0		0x40B00000
+#define PWM1		0x40C00000
+#define PWM0slave	0x40B00010
+#define PWM1slave	0x40C00010
+
+#endif

arch/arm/mach-pxa/speed-pxa27x.c

@@ -47,3 +47,8 @@ unsigned long pxa_get_lcdclk(void)
 {
 	return pxa_get_lcdclk_10khz() * 10000;
 }
+
+unsigned long pxa_get_pwmclk(void)
+{
+	return BASE_CLK;
+}

drivers/pwm/Kconfig

@@ -8,5 +8,11 @@ menuconfig PWM
 	  If unsure, say N.
 
 if PWM
+config PWM_PXA
+	bool "PXA PWM Support"
+	default y if ARCH_PXA2XX
+	help
+	  This enables PWM support for Intel/Marvell PXA chips, such
+	  as the PXA25x, PXA27x.
 
 endif

drivers/pwm/Makefile

@@ -1 +1,2 @@
 obj-$(CONFIG_PWM)		+= core.o
+obj-$(CONFIG_PWM_PXA)		+= pxa_pwm.o

drivers/pwm/pxa_pwm.c

@@ -0,0 +1,157 @@
+/*
+ * simple driver for PWM (Pulse Width Modulator) controller
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 2008-02-13	initial version eric miao <eric.miao@marvell.com>
+ * 2012         Robert Jarzmik <robert.jarzmik@free.fr>
+ */
+
+#include <common.h>
+#include <init.h>
+#include <errno.h>
+#include <io.h>
+#include <pwm.h>
+
+#include <mach/hardware.h>
+#include <mach/clock.h>
+#include <mach/pxa-regs.h>
+#include <mach/regs-pwm.h>
+#include <asm-generic/div64.h>
+#include <linux/compiler.h>
+
+/* PWM registers and bits definitions */
+#define PWMCR		(0x00)
+#define PWMDCR		(0x04)
+#define PWMPCR		(0x08)
+
+#define PWMCR_SD	(1 << 6)
+#define PWMDCR_FD	(1 << 10)
+
+struct pxa_pwm_chip {
+	struct pwm_chip chip;
+	void __iomem *iobase;
+	int id;
+	int duty_ns;
+	int period_ns;
+};
+
+static struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct pxa_pwm_chip, chip);
+}
+
+/*
+ * period_ns    = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
+ * duty_ns      = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
+ * PWM_CLK_RATE = 13 MHz
+ */
+static int pxa_pwm_config(struct pwm_chip *chip, int duty_ns, int period_ns)
+{
+	unsigned long long c;
+	unsigned long period_cycles, prescale, pv, dc;
+	struct pxa_pwm_chip *pxa_pwm = to_pxa_pwm_chip(chip);
+
+	c = pxa_get_pwmclk();
+	c = c * period_ns;
+	do_div(c, 1000000000);
+	period_cycles = c;
+
+	if (period_cycles < 1)
+		period_cycles = 1;
+	prescale = (period_cycles - 1) / 1024;
+	pv = period_cycles / (prescale + 1) - 1;
+
+	if (prescale > 63)
+		return -EINVAL;
+
+	if (duty_ns == period_ns)
+		dc = PWMDCR_FD;
+	else
+		dc = (pv + 1) * duty_ns / period_ns;
+
+	pxa_pwm->duty_ns = duty_ns;
+	pxa_pwm->period_ns = period_ns;
+
+	/* NOTE: the clock to PWM has to be enabled first
+	 * before writing to the registers
+	 */
+	__raw_writel(prescale, pxa_pwm->iobase + PWMCR);
+	__raw_writel(dc, pxa_pwm->iobase + PWMDCR);
+	__raw_writel(pv, pxa_pwm->iobase + PWMPCR);
+
+	return 0;
+}
+
+static int pxa_pwm_enable(struct pwm_chip *chip)
+{
+	struct pxa_pwm_chip *pxa_pwm = to_pxa_pwm_chip(chip);
+
+	switch (pxa_pwm->id) {
+	case 0:
+	case 2:
+		CKEN |= CKEN_PWM0;
+		break;
+	case 1:
+	case 3:
+		CKEN |= CKEN_PWM1;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static void pxa_pwm_disable(struct pwm_chip *chip)
+{
+	struct pxa_pwm_chip *pxa_pwm = to_pxa_pwm_chip(chip);
+
+	switch (pxa_pwm->id) {
+	case 0:
+	case 2:
+		CKEN &= ~CKEN_PWM0;
+		break;
+	case 1:
+	case 3:
+		CKEN &= ~CKEN_PWM1;
+		break;
+	default:
+		break;
+	}
+}
+
+static struct pwm_ops pxa_pwm_ops = {
+	.config = pxa_pwm_config,
+	.enable = pxa_pwm_enable,
+	.disable = pxa_pwm_disable,
+};
+
+static int pxa_pwm_probe(struct device_d *dev)
+{
+	struct pxa_pwm_chip *chip;
+
+	chip = xzalloc(sizeof(*chip));
+	chip->chip.devname = asprintf("%s", dev_name(dev));
+	chip->chip.ops = &pxa_pwm_ops;
+	chip->iobase = dev_request_mem_region(dev, 0);
+	chip->id = dev->id;
+	dev->priv = chip;
+
+	return pwmchip_add(&chip->chip, dev);
+}
+
+static struct driver_d pxa_pwm_driver = {
+	.name  = "pxa_pwm",
+	.probe = pxa_pwm_probe,
+};
+
+static int __init pxa_pwm_init_driver(void)
+{
+	CKEN &= ~CKEN_PWM0 & ~CKEN_PWM1;
+	register_driver(&pxa_pwm_driver);
+	return 0;
+}
+
+device_initcall(pxa_pwm_init_driver);