[rfc]pwm: add BCM2835 PWM driver

[Bart Tanghe]

need some recommendation
the memory mapped io registers of the bcm2835 pwm hardware are spreaded 
over the memory mapped io 
gpio config 0x20200004 - clk config 0x201010A0 - pwm configuration 0x2020C000
to handle this, I've used the base address of the memory mapped io 
so I can use positive offsets

this give some nasty stuff in for instance, /proc/iomem
Has anyone got a nice solution?

Signed-off-by: Bart Tanghe <bart.tanghe@xxxxxxxxxxxxx>
---
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 22f2f28..977e5f6 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -62,6 +62,17 @@ config PWM_ATMEL_TCB
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-atmel-tcb.
 
+config PWM_BCM2835
+	tristate "BCM2835 PWM support"
+	depends on ARCH_BCM2835 || ARCH_BCM2708
+	help
+	  PWM framework driver for BCM2835 controller (raspberry pi)
+
+	  The pwm core frequency is set on 1Mhz, period above 1000 are accepted.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-bcm2835.
+
 config PWM_BFIN
 	tristate "Blackfin PWM support"
 	depends on BFIN_GPTIMERS
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index d8906ec..9863590 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_PWM_SYSFS)		+= sysfs.o
 obj-$(CONFIG_PWM_AB8500)	+= pwm-ab8500.o
 obj-$(CONFIG_PWM_ATMEL)		+= pwm-atmel.o
 obj-$(CONFIG_PWM_ATMEL_TCB)	+= pwm-atmel-tcb.o
+obj-$(CONFIG_PWM_BCM2835)	+= pwm-bcm2835.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
 obj-$(CONFIG_PWM_EP93XX)	+= pwm-ep93xx.o
 obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
new file mode 100644
index 0000000..29d7108
--- /dev/null
+++ b/drivers/pwm/pwm-bcm2835.c
@@ -0,0 +1,300 @@
+/*
+ * pwm-bcm2835 driver
+ * Standard raspberry pi (gpio18 - pwm0)
+ *
+ * Copyright (C) 2014 Thomas more
+ *
+ */
+
+/*#define DEBUG*/
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+/*mmio regiser mapping*/
+#define OFFSET_PWM		0x0020C000
+#define DUTY			0x14
+#define PERIOD			0x10
+#define CHANNEL		0x10
+
+#define OFFSET_CLK		0x001010A0
+#define DIV			0x04
+
+#define OFFSET_ALT		0x00200004
+
+/*Value defines*/
+/*pwm clock configuration*/
+#define PWMCLK_CNTL_OFF (0x5A000000 | (1 << 5))
+#define PWMCLK_CNTL_ON (0x5A000000 | 0x11)
+
+#define PWM_ENABLE	0x00000001
+#define PWM_POLARITY	0x00000010
+/*+-1MHz pwm clock*/
+#define PWMCLK_DIV 	(0x5A000000 | (19 << 12))
+/*ALT5 mask gpio18*/
+#define ALTOR		0x02000000
+#define ALTAND		0xFAFFFFFF
+/*pwm configuration*/
+#define MASK_CTL_PWM 	0x000000FF
+#define CTL_PWM 	0x00000081
+
+#define DRIVER_AUTHOR "Bart Tanghe <bart.tanghe@xxxxxxxxxxxxx>"
+#define DRIVER_DESC   "A bcm2835 pwm driver - raspberry pi development platform\
+- only gpio 18 channel0 available"
+
+unsigned long *ptrPWM;
+unsigned long *ptrPERIOD;
+unsigned long *ptrDUTY;
+unsigned long *ptrCLK;
+unsigned long *ptrALT;
+unsigned long *ptrDIV;
+
+struct bcm2835_pwm_chip {
+	struct pwm_chip chip;
+	struct device *dev;
+	int channel;
+	void __iomem *mmio;
+};
+
+static inline struct bcm2835_pwm_chip *to_bcm2835_pwm_chip(
+struct pwm_chip *chip){
+	return container_of(chip, struct bcm2835_pwm_chip, chip);
+}
+
+static int bcm2835_pwm_config(struct pwm_chip *chip,
+struct pwm_device *pwm, int duty_ns, int period_ns){
+
+	struct bcm2835_pwm_chip *pc;
+
+	pc = container_of(chip, struct bcm2835_pwm_chip, chip);
+
+	iowrite32(duty_ns/1000, ptrDUTY);
+	iowrite32(period_ns/1000, ptrPERIOD);
+
+	#ifdef DEBUG
+		printk(KERN_DEBUG "period %x\n", (unsigned int)ptrPERIOD);
+		printk(KERN_DEBUG "duty %x\n", (unsigned int)ptrDUTY);
+	#endif
+
+	return 0;
+}
+
+static int bcm2835_pwm_enable(struct pwm_chip *chip,
+struct pwm_device *pwm){
+	struct bcm2835_pwm_chip *pc;
+
+	pc = container_of(chip, struct bcm2835_pwm_chip, chip);
+
+	/*TODO: channel 1 enable*/
+	#ifdef DEBUG
+		printk(KERN_DEBUG "pwm label: %s\n", pwm->label);
+		printk(KERN_DEBUG "pwm hwpwm: %d\n", pwm->hwpwm);
+		printk(KERN_DEBUG "pwm pwm: %d\n", pwm->pwm);
+	#endif
+
+	iowrite32(ioread32(ptrPWM) | PWM_ENABLE, ptrPWM);
+	#ifdef DEBUG
+		printk(KERN_DEBUG "pwm: %x\n", ioread32(ptrPWM));
+	#endif
+	return 0;
+}
+
+static void bcm2835_pwm_disable(struct pwm_chip *chip,
+			struct pwm_device *pwm)
+{
+	struct bcm2835_pwm_chip *pc;
+
+	pc = to_bcm2835_pwm_chip(chip);
+
+	#ifdef DEBUG
+		printk(KERN_DEBUG "pwm label: %s\n", pwm->label);
+		printk(KERN_DEBUG "pwm hwpwm: %d\n", pwm->hwpwm);
+		printk(KERN_DEBUG "pwm pwm: %d\n", pwm->pwm);
+	#endif
+
+	iowrite32(ioread32(ptrPWM) & ~PWM_ENABLE, ptrPWM);
+}
+
+static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
+enum pwm_polarity polarity)
+{
+	if (polarity == PWM_POLARITY_NORMAL)
+		iowrite32((ioread32(ptrPWM) & ~PWM_POLARITY), ptrPWM);
+	else if (polarity == PWM_POLARITY_INVERSED)
+		iowrite32((ioread32(ptrPWM) | PWM_POLARITY), ptrPWM);
+
+	return 0;
+}
+
+static const struct pwm_ops bcm2835_pwm_ops = {
+	.config = bcm2835_pwm_config,
+	.enable = bcm2835_pwm_enable,
+	.disable = bcm2835_pwm_disable,
+	.set_polarity = bcm2835_set_polarity,
+	.owner = THIS_MODULE,
+};
+
+static int bcm2835_pwm_probe(struct platform_device *pdev)
+{
+	struct bcm2835_pwm_chip *pwm;
+
+	int ret;
+	struct resource *r;
+	u32 start, end;
+
+	printk(KERN_DEBUG "pwm probe\n");
+
+	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+	if (!pwm) {
+		dev_err(&pdev->dev, "failed to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	pwm->dev = &pdev->dev;
+
+	#ifdef DEBUG
+		printk(KERN_DEBUG "id:%d\n", pdev->id);
+	#endif
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	pwm->mmio = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(pwm->mmio))
+		return PTR_ERR(pwm->mmio);
+
+	start = r->start;
+	end = r->end;
+
+	#ifdef DEBUG
+		printk(KERN_DEBUG "mmio base start: %x stop:%x\n",
+			(unsigned int)start, (unsigned int)end);
+	#endif
+
+	platform_set_drvdata(pdev, pwm);
+
+	pwm->chip.dev = &pdev->dev;
+	pwm->chip.ops = &bcm2835_pwm_ops;
+	pwm->chip.npwm = 1;
+
+	ret = pwmchip_add(&pwm->chip);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
+		goto chip_failed;
+	}
+
+	ptrPWM = (long *)ioremap_nocache(start + OFFSET_PWM, 4);
+	if (ptrPWM == NULL) {
+		printk(KERN_ERR "ioremap REG_PWM failed\n");
+		goto map_failed;
+	}
+
+	ptrDUTY = (long *)ioremap_nocache(start + OFFSET_PWM + DUTY, 4);
+	if (ptrDUTY == NULL) {
+		printk(KERN_ERR "ioremap REG_DUTY failed\n");
+		goto map_failed;
+	}
+
+	ptrPERIOD = (long *)ioremap_nocache(
+		start + OFFSET_PWM + PERIOD, 4);
+	if (ptrDUTY == NULL) {
+		printk(KERN_ERR "ioremap REG_DUTY failed\n");
+		goto map_failed;
+	}
+
+	ptrCLK = (long *)ioremap_nocache(start + OFFSET_CLK, 4);
+	if (ptrCLK == NULL) {
+		printk(KERN_ERR "ioremap PWMCLK_CNTL failed\n");
+		goto map_failed;
+	}
+
+	ptrALT = (long *)ioremap_nocache(start + OFFSET_ALT, 4);
+	if (ptrALT == NULL) {
+		printk(KERN_ERR "ioremap FUNC_SLCT_HEAT_PWM failed\n");
+		goto map_failed;
+	}
+
+	ptrDIV = (long *)ioremap_nocache(start + OFFSET_CLK + DIV, 4);
+	if (ptrALT == NULL) {
+		printk(KERN_ERR "ioremap pwmDIV failed\n");
+		goto map_failed;
+	}
+
+	#ifdef DEBUG
+		printk(KERN_DEBUG "io mem adres:%x %x %x\n",
+			(unsigned int)start+OFFSET_PWM, (unsigned int)start +
+			OFFSET_CLK, (unsigned int)start + OFFSET_ALT);
+		printk(KERN_DEBUG "%x %x %x\n", (unsigned int)ptrPWM,
+			(unsigned int)ptrCLK, (unsigned int)ptrALT);
+	#endif
+
+
+	iowrite32((ioread32(ptrALT) & ALTAND) | ALTOR, ptrALT);
+	/*disable the clock to set the dividere*/
+	iowrite32(PWMCLK_CNTL_OFF, ptrCLK);
+	/*pwm clock set to 1Mhz.*/
+	iowrite32(PWMCLK_DIV, ptrDIV);
+	/*enable the clock, load the new configuration*/
+	iowrite32(PWMCLK_CNTL_ON, ptrCLK);
+	/*set the pwm0 configuration*/
+	iowrite32((ioread32(ptrPWM) & ~MASK_CTL_PWM) | CTL_PWM, ptrPWM);
+
+	#ifdef DEBUG
+		/*duty cycle 1ms*/
+		iowrite32(100000/1000, (unsigned long *)ptrDUTY);
+		/*period 300 us*/
+		iowrite32(300000/1000, (unsigned long *)ptrPERIOD);
+		iowrite32(ioread32(ptrPWM) | PWM_ENABLE, ptrPWM);
+	#endif
+
+	return 0;
+
+map_failed:
+	pwmchip_remove(&pwm->chip);
+
+chip_failed:
+	devm_kfree(&pdev->dev, pwm);
+	return -1;
+
+}
+
+static int bcm2835_pwm_remove(struct platform_device *pdev)
+{
+
+	struct bcm2835_pwm_chip *pc;
+	pc  = platform_get_drvdata(pdev);
+
+	if (WARN_ON(!pc))
+		return -ENODEV;
+
+	iounmap(ptrALT);
+	iounmap(ptrPWM);
+	iounmap(ptrCLK);
+	iounmap(ptrDUTY);
+	iounmap(ptrPERIOD);
+
+
+	return pwmchip_remove(&pc->chip);
+}
+
+static const struct of_device_id bcm2835_pwm_of_match[] = {
+	{ .compatible = "rpi,pwm-bcm2835" },
+	{ }
+};
+
+static struct platform_driver bcm2835_pwm_driver = {
+	.driver = {
+		.name = "pwm-bcm2835",
+		.owner = THIS_MODULE,
+		.of_match_table = bcm2835_pwm_of_match,
+	},
+	.probe = bcm2835_pwm_probe,
+	.remove = bcm2835_pwm_remove,
+};
+module_platform_driver(bcm2835_pwm_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR(DRIVER_AUTHOR);
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