2 * simple driver for PWM (Pulse Width Modulator) controller
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
8 * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/platform_device.h>
14 #include <linux/err.h>
15 #include <linux/clk.h>
17 #include <linux/pwm.h>
18 #include <mach/hardware.h>
21 /* i.MX1 and i.MX21 share the same PWM function block: */
23 #define MX1_PWMC 0x00 /* PWM Control Register */
24 #define MX1_PWMS 0x04 /* PWM Sample Register */
25 #define MX1_PWMP 0x08 /* PWM Period Register */
28 /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
30 #define MX3_PWMCR 0x00 /* PWM Control Register */
31 #define MX3_PWMSAR 0x0C /* PWM Sample Register */
32 #define MX3_PWMPR 0x10 /* PWM Period Register */
33 #define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)
34 #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
35 #define MX3_PWMCR_CLKSRC_IPG (1 << 16)
36 #define MX3_PWMCR_EN (1 << 0)
41 struct list_head node;
42 struct platform_device *pdev;
48 void __iomem *mmio_base;
50 unsigned int use_count;
54 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
56 if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
59 if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25()) {
61 unsigned long period_cycles, duty_cycles, prescale;
64 c = clk_get_rate(pwm->clk);
66 do_div(c, 1000000000);
69 prescale = period_cycles / 0x10000 + 1;
71 period_cycles /= prescale;
72 c = (unsigned long long)period_cycles * duty_ns;
76 writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
77 writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
79 cr = MX3_PWMCR_PRESCALER(prescale) | MX3_PWMCR_EN;
82 cr |= MX3_PWMCR_CLKSRC_IPG;
84 cr |= MX3_PWMCR_CLKSRC_IPG_HIGH;
86 writel(cr, pwm->mmio_base + MX3_PWMCR);
87 } else if (cpu_is_mx1() || cpu_is_mx21()) {
88 /* The PWM subsystem allows for exact frequencies. However,
89 * I cannot connect a scope on my device to the PWM line and
90 * thus cannot provide the program the PWM controller
91 * exactly. Instead, I'm relying on the fact that the
92 * Bootloader (u-boot or WinCE+haret) has programmed the PWM
93 * function group already. So I'll just modify the PWM sample
94 * register to follow the ratio of duty_ns vs. period_ns
97 * This is good enough for programming the brightness of
100 * The real implementation would divide PERCLK[0] first by
101 * both the prescaler (/1 .. /128) and then by CLKSEL
104 u32 max = readl(pwm->mmio_base + MX1_PWMP);
105 u32 p = max * duty_ns / period_ns;
106 writel(max - p, pwm->mmio_base + MX1_PWMS);
113 EXPORT_SYMBOL(pwm_config);
115 int pwm_enable(struct pwm_device *pwm)
119 if (!pwm->clk_enabled) {
120 rc = clk_enable(pwm->clk);
122 pwm->clk_enabled = 1;
126 EXPORT_SYMBOL(pwm_enable);
128 void pwm_disable(struct pwm_device *pwm)
130 writel(0, pwm->mmio_base + MX3_PWMCR);
132 if (pwm->clk_enabled) {
133 clk_disable(pwm->clk);
134 pwm->clk_enabled = 0;
137 EXPORT_SYMBOL(pwm_disable);
139 static DEFINE_MUTEX(pwm_lock);
140 static LIST_HEAD(pwm_list);
142 struct pwm_device *pwm_request(int pwm_id, const char *label)
144 struct pwm_device *pwm;
147 mutex_lock(&pwm_lock);
149 list_for_each_entry(pwm, &pwm_list, node) {
150 if (pwm->pwm_id == pwm_id) {
157 if (pwm->use_count == 0) {
161 pwm = ERR_PTR(-EBUSY);
163 pwm = ERR_PTR(-ENOENT);
165 mutex_unlock(&pwm_lock);
168 EXPORT_SYMBOL(pwm_request);
170 void pwm_free(struct pwm_device *pwm)
172 mutex_lock(&pwm_lock);
174 if (pwm->use_count) {
178 pr_warning("PWM device already freed\n");
180 mutex_unlock(&pwm_lock);
182 EXPORT_SYMBOL(pwm_free);
184 static int __devinit mxc_pwm_probe(struct platform_device *pdev)
186 struct pwm_device *pwm;
190 pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
192 dev_err(&pdev->dev, "failed to allocate memory\n");
196 pwm->clk = clk_get(&pdev->dev, "pwm");
198 if (IS_ERR(pwm->clk)) {
199 ret = PTR_ERR(pwm->clk);
203 pwm->clk_enabled = 0;
206 pwm->pwm_id = pdev->id;
209 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
211 dev_err(&pdev->dev, "no memory resource defined\n");
216 r = request_mem_region(r->start, r->end - r->start + 1, pdev->name);
218 dev_err(&pdev->dev, "failed to request memory resource\n");
223 pwm->mmio_base = ioremap(r->start, r->end - r->start + 1);
224 if (pwm->mmio_base == NULL) {
225 dev_err(&pdev->dev, "failed to ioremap() registers\n");
230 mutex_lock(&pwm_lock);
231 list_add_tail(&pwm->node, &pwm_list);
232 mutex_unlock(&pwm_lock);
234 platform_set_drvdata(pdev, pwm);
238 release_mem_region(r->start, r->end - r->start + 1);
246 static int __devexit mxc_pwm_remove(struct platform_device *pdev)
248 struct pwm_device *pwm;
251 pwm = platform_get_drvdata(pdev);
255 mutex_lock(&pwm_lock);
256 list_del(&pwm->node);
257 mutex_unlock(&pwm_lock);
259 iounmap(pwm->mmio_base);
261 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
262 release_mem_region(r->start, r->end - r->start + 1);
270 static struct platform_driver mxc_pwm_driver = {
274 .probe = mxc_pwm_probe,
275 .remove = __devexit_p(mxc_pwm_remove),
278 static int __init mxc_pwm_init(void)
280 return platform_driver_register(&mxc_pwm_driver);
282 arch_initcall(mxc_pwm_init);
284 static void __exit mxc_pwm_exit(void)
286 platform_driver_unregister(&mxc_pwm_driver);
288 module_exit(mxc_pwm_exit);
290 MODULE_LICENSE("GPL v2");
291 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");