From 9de00286e20a5f5edc419698373010f1cb6ff0ce Mon Sep 17 00:00:00 2001
From: John Crispin <blogic@openwrt.org>
Date: Sun, 27 Jul 2014 09:25:02 +0100
Subject: [PATCH 19/57] MIPS: ralink: add pseudo pwm led trigger based on
 timer0

Signed-off-by: John Crispin <blogic@openwrt.org>
---
 arch/mips/ralink/timer.c |  213 ++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 197 insertions(+), 16 deletions(-)

--- a/arch/mips/ralink/timer.c
+++ b/arch/mips/ralink/timer.c
@@ -12,6 +12,8 @@
 #include <linux/timer.h>
 #include <linux/of_gpio.h>
 #include <linux/clk.h>
+#include <linux/leds.h>
+#include <linux/slab.h>
 
 #include <asm/mach-ralink/ralink_regs.h>
 
@@ -23,16 +25,34 @@
 
 #define TMR0CTL_ENABLE			BIT(7)
 #define TMR0CTL_MODE_PERIODIC		BIT(4)
-#define TMR0CTL_PRESCALER		1
+#define TMR0CTL_PRESCALER		2
 #define TMR0CTL_PRESCALE_VAL		(0xf - TMR0CTL_PRESCALER)
 #define TMR0CTL_PRESCALE_DIV		(65536 / BIT(TMR0CTL_PRESCALER))
 
+struct rt_timer_gpio {
+	struct list_head	list;
+	struct led_classdev	*led;
+};
+
 struct rt_timer {
-	struct device	*dev;
-	void __iomem	*membase;
-	int		irq;
-	unsigned long	timer_freq;
-	unsigned long	timer_div;
+	struct device		*dev;
+	void __iomem		*membase;
+	int			irq;
+
+	unsigned long		timer_freq;
+	unsigned long		timer_div;
+
+	struct list_head	gpios;
+	struct led_trigger	led_trigger;
+	unsigned int		duty_cycle;
+	unsigned int		duty;
+
+	unsigned int		fade;
+	unsigned int		fade_min;
+	unsigned int		fade_max;
+	unsigned int		fade_speed;
+	unsigned int		fade_dir;
+	unsigned int		fade_count;
 };
 
 static inline void rt_timer_w32(struct rt_timer *rt, u8 reg, u32 val)
@@ -48,8 +68,37 @@ static inline u32 rt_timer_r32(struct rt
 static irqreturn_t rt_timer_irq(int irq, void *_rt)
 {
 	struct rt_timer *rt =  (struct rt_timer *) _rt;
+	struct rt_timer_gpio *gpio;
+	unsigned int val;
 
-	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
+	if (rt->fade && (rt->fade_count++ > rt->fade_speed)) {
+		rt->fade_count = 0;
+		if (rt->duty_cycle <= rt->fade_min)
+			rt->fade_dir = 1;
+		else if (rt->duty_cycle >= rt->fade_max)
+			rt->fade_dir = 0;
+
+		if (rt->fade_dir)
+			rt->duty_cycle += 1;
+		else
+			rt->duty_cycle -= 1;
+
+	}
+
+	val = rt->timer_freq / rt->timer_div;
+	if (rt->duty)
+		val *= rt->duty_cycle;
+	else
+		val *= (100 - rt->duty_cycle);
+	val /= 100;
+
+	if (!list_empty(&rt->gpios))
+		list_for_each_entry(gpio, &rt->gpios, list)
+			led_set_brightness(gpio->led, !!rt->duty);
+
+	rt->duty = !rt->duty;
+
+	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, val + 1);
 	rt_timer_w32(rt, TIMER_REG_TMRSTAT, TMRSTAT_TMR0INT);
 
 	return IRQ_HANDLED;
@@ -58,8 +107,8 @@ static irqreturn_t rt_timer_irq(int irq,
 
 static int rt_timer_request(struct rt_timer *rt)
 {
-	int err = request_irq(rt->irq, rt_timer_irq, 0,
-						dev_name(rt->dev), rt);
+	int err = devm_request_irq(rt->dev, rt->irq, rt_timer_irq,
+					0, dev_name(rt->dev), rt);
 	if (err) {
 		dev_err(rt->dev, "failed to request irq\n");
 	} else {
@@ -81,8 +130,6 @@ static int rt_timer_config(struct rt_tim
 	else
 		rt->timer_div = divisor;
 
-	rt_timer_w32(rt, TIMER_REG_TMR0LOAD, rt->timer_freq / rt->timer_div);
-
 	return 0;
 }
 
@@ -108,11 +155,128 @@ static void rt_timer_disable(struct rt_t
 	rt_timer_w32(rt, TIMER_REG_TMR0CTL, t);
 }
 
+static ssize_t led_fade_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct rt_timer *rt = container_of(led_cdev->trigger, struct rt_timer, led_trigger);
+
+	return sprintf(buf, "speed: %d, min: %d, max: %d\n", rt->fade_speed, rt->fade_min, rt->fade_max);
+}
+
+static ssize_t led_fade_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct rt_timer *rt = container_of(led_cdev->trigger, struct rt_timer, led_trigger);
+	unsigned int speed = 0, min = 0, max = 0;
+	ssize_t ret = -EINVAL;
+
+	ret = sscanf(buf, "%u %u %u", &speed, &min, &max);
+
+	if (ret == 3) {
+		rt->fade_speed = speed;
+		rt->fade_min = min;
+		rt->fade_max = max;
+		rt->fade = 1;
+	} else {
+		rt->fade = 0;
+	}
+
+	return size;
+}
+
+static DEVICE_ATTR(fade, 0644, led_fade_show, led_fade_store);
+
+static ssize_t led_duty_cycle_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct rt_timer *rt = container_of(led_cdev->trigger, struct rt_timer, led_trigger);
+
+	return sprintf(buf, "%u\n", rt->duty_cycle);
+}
+
+static ssize_t led_duty_cycle_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct rt_timer *rt = container_of(led_cdev->trigger, struct rt_timer, led_trigger);
+	unsigned long state;
+	ssize_t ret = -EINVAL;
+
+	ret = kstrtoul(buf, 10, &state);
+	if (ret)
+		return ret;
+
+	if (state <= 100)
+		rt->duty_cycle = state;
+	else
+		rt->duty_cycle = 100;
+
+	rt->fade = 0;
+
+	return size;
+}
+
+static DEVICE_ATTR(duty_cycle, 0644, led_duty_cycle_show, led_duty_cycle_store);
+
+static void rt_timer_trig_activate(struct led_classdev *led_cdev)
+{
+	struct rt_timer *rt = container_of(led_cdev->trigger, struct rt_timer, led_trigger);
+	struct rt_timer_gpio *gpio_data;
+	int rc;
+
+	led_cdev->trigger_data = NULL;
+	gpio_data = kzalloc(sizeof(*gpio_data), GFP_KERNEL);
+	if (!gpio_data)
+		return;
+
+	rc = device_create_file(led_cdev->dev, &dev_attr_duty_cycle);
+	if (rc)
+		goto err_gpio;
+	rc = device_create_file(led_cdev->dev, &dev_attr_fade);
+	if (rc)
+		goto err_out_duty_cycle;
+
+	led_cdev->activated = true;
+	led_cdev->trigger_data = gpio_data;
+	gpio_data->led = led_cdev;
+	list_add(&gpio_data->list, &rt->gpios);
+	led_cdev->trigger_data = gpio_data;
+	rt_timer_enable(rt);
+	return;
+
+err_out_duty_cycle:
+	device_remove_file(led_cdev->dev, &dev_attr_duty_cycle);
+
+err_gpio:
+	kfree(gpio_data);
+}
+
+static void rt_timer_trig_deactivate(struct led_classdev *led_cdev)
+{
+	struct rt_timer *rt = container_of(led_cdev->trigger, struct rt_timer, led_trigger);
+	struct rt_timer_gpio *gpio_data = (struct rt_timer_gpio*) led_cdev->trigger_data;
+
+	if (led_cdev->activated) {
+		device_remove_file(led_cdev->dev, &dev_attr_duty_cycle);
+		device_remove_file(led_cdev->dev, &dev_attr_fade);
+		led_cdev->activated = false;
+	}
+
+	list_del(&gpio_data->list);
+	rt_timer_disable(rt);
+	led_set_brightness(led_cdev, LED_OFF);
+}
+
 static int rt_timer_probe(struct platform_device *pdev)
 {
 	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	const __be32 *divisor;
 	struct rt_timer *rt;
 	struct clk *clk;
+	int ret;
 
 	rt = devm_kzalloc(&pdev->dev, sizeof(*rt), GFP_KERNEL);
 	if (!rt) {
@@ -140,12 +304,29 @@ static int rt_timer_probe(struct platfor
 	if (!rt->timer_freq)
 		return -EINVAL;
 
+	rt->duty_cycle = 100;
 	rt->dev = &pdev->dev;
 	platform_set_drvdata(pdev, rt);
 
-	rt_timer_request(rt);
-	rt_timer_config(rt, 2);
-	rt_timer_enable(rt);
+	ret = rt_timer_request(rt);
+	if (ret)
+		return ret;
+
+	divisor = of_get_property(pdev->dev.of_node, "ralink,divisor", NULL);
+	if (divisor)
+		rt_timer_config(rt, be32_to_cpu(*divisor));
+	else
+		rt_timer_config(rt, 200);
+
+	rt->led_trigger.name = "pwmtimer",
+	rt->led_trigger.activate = rt_timer_trig_activate,
+	rt->led_trigger.deactivate = rt_timer_trig_deactivate,
+
+	ret = led_trigger_register(&rt->led_trigger);
+	if (ret)
+		return ret;
+
+	INIT_LIST_HEAD(&rt->gpios);
 
 	dev_info(&pdev->dev, "maximum frequency is %luHz\n", rt->timer_freq);
 
@@ -156,6 +337,7 @@ static int rt_timer_remove(struct platfo
 {
 	struct rt_timer *rt = platform_get_drvdata(pdev);
 
+	led_trigger_unregister(&rt->led_trigger);
 	rt_timer_disable(rt);
 	rt_timer_free(rt);
 
@@ -180,6 +362,6 @@ static struct platform_driver rt_timer_d
 
 module_platform_driver(rt_timer_driver);
 
-MODULE_DESCRIPTION("Ralink RT2880 timer");
+MODULE_DESCRIPTION("Ralink RT2880 timer / pseudo pwm");
 MODULE_AUTHOR("John Crispin <blogic@openwrt.org");
 MODULE_LICENSE("GPL");
