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/slab.h>
15 #include <linux/err.h>
16 #include <linux/clk.h>
18 #include <linux/pwm.h>
19 #include <mach/hardware.h>
22 /* i.MX1 and i.MX21 share the same PWM function block: */
24 #define MX1_PWMC 0x00 /* PWM Control Register */
25 #define MX1_PWMS 0x04 /* PWM Sample Register */
26 #define MX1_PWMP 0x08 /* PWM Period Register */
29 /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
31 #define MX3_PWMCR 0x00 /* PWM Control Register */
32 #define MX3_PWMSAR 0x0C /* PWM Sample Register */
33 #define MX3_PWMPR 0x10 /* PWM Period Register */
34 #define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)
35 #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
36 #define MX3_PWMCR_CLKSRC_IPG (1 << 16)
37 #define MX3_PWMCR_EN (1 << 0)
42 struct list_head node;
43 struct platform_device *pdev;
49 void __iomem *mmio_base;
51 unsigned int use_count;
55 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
57 if (pwm == NULL || period_ns == 0 || duty_ns > period_ns)
60 if (cpu_is_mx27() || cpu_is_mx3() || cpu_is_mx25() || cpu_is_mx51()) {
62 unsigned long period_cycles, duty_cycles, prescale;
65 c = clk_get_rate(pwm->clk);
67 do_div(c, 1000000000);
70 prescale = period_cycles / 0x10000 + 1;
72 period_cycles /= prescale;
73 c = (unsigned long long)period_cycles * duty_ns;
77 writel(duty_cycles, pwm->mmio_base + MX3_PWMSAR);
78 writel(period_cycles, pwm->mmio_base + MX3_PWMPR);
80 cr = MX3_PWMCR_PRESCALER(prescale) | MX3_PWMCR_EN;
83 cr |= MX3_PWMCR_CLKSRC_IPG;
85 cr |= MX3_PWMCR_CLKSRC_IPG_HIGH;
87 writel(cr, pwm->mmio_base + MX3_PWMCR);
88 } else if (cpu_is_mx1() || cpu_is_mx21()) {
89 /* The PWM subsystem allows for exact frequencies. However,
90 * I cannot connect a scope on my device to the PWM line and
91 * thus cannot provide the program the PWM controller
92 * exactly. Instead, I'm relying on the fact that the
93 * Bootloader (u-boot or WinCE+haret) has programmed the PWM
94 * function group already. So I'll just modify the PWM sample
95 * register to follow the ratio of duty_ns vs. period_ns
98 * This is good enough for programming the brightness of
101 * The real implementation would divide PERCLK[0] first by
102 * both the prescaler (/1 .. /128) and then by CLKSEL
105 u32 max = readl(pwm->mmio_base + MX1_PWMP);
106 u32 p = max * duty_ns / period_ns;
107 writel(max - p, pwm->mmio_base + MX1_PWMS);
114 EXPORT_SYMBOL(pwm_config);
116 int pwm_enable(struct pwm_device *pwm)
120 if (!pwm->clk_enabled) {
121 rc = clk_enable(pwm->clk);
123 pwm->clk_enabled = 1;
127 EXPORT_SYMBOL(pwm_enable);
129 void pwm_disable(struct pwm_device *pwm)
131 writel(0, pwm->mmio_base + MX3_PWMCR);
133 if (pwm->clk_enabled) {
134 clk_disable(pwm->clk);
135 pwm->clk_enabled = 0;
138 EXPORT_SYMBOL(pwm_disable);
140 static DEFINE_MUTEX(pwm_lock);
141 static LIST_HEAD(pwm_list);
143 struct pwm_device *pwm_request(int pwm_id, const char *label)
145 struct pwm_device *pwm;
148 mutex_lock(&pwm_lock);
150 list_for_each_entry(pwm, &pwm_list, node) {
151 if (pwm->pwm_id == pwm_id) {
158 if (pwm->use_count == 0) {
162 pwm = ERR_PTR(-EBUSY);
164 pwm = ERR_PTR(-ENOENT);
166 mutex_unlock(&pwm_lock);
169 EXPORT_SYMBOL(pwm_request);
171 void pwm_free(struct pwm_device *pwm)
173 mutex_lock(&pwm_lock);
175 if (pwm->use_count) {
179 pr_warning("PWM device already freed\n");
181 mutex_unlock(&pwm_lock);
183 EXPORT_SYMBOL(pwm_free);
185 static int __devinit mxc_pwm_probe(struct platform_device *pdev)
187 struct pwm_device *pwm;
191 pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
193 dev_err(&pdev->dev, "failed to allocate memory\n");
197 pwm->clk = clk_get(&pdev->dev, "pwm");
199 if (IS_ERR(pwm->clk)) {
200 ret = PTR_ERR(pwm->clk);
204 pwm->clk_enabled = 0;
207 pwm->pwm_id = pdev->id;
210 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
212 dev_err(&pdev->dev, "no memory resource defined\n");
217 r = request_mem_region(r->start, r->end - r->start + 1, pdev->name);
219 dev_err(&pdev->dev, "failed to request memory resource\n");
224 pwm->mmio_base = ioremap(r->start, r->end - r->start + 1);
225 if (pwm->mmio_base == NULL) {
226 dev_err(&pdev->dev, "failed to ioremap() registers\n");
231 mutex_lock(&pwm_lock);
232 list_add_tail(&pwm->node, &pwm_list);
233 mutex_unlock(&pwm_lock);
235 platform_set_drvdata(pdev, pwm);
239 release_mem_region(r->start, r->end - r->start + 1);
247 static int __devexit mxc_pwm_remove(struct platform_device *pdev)
249 struct pwm_device *pwm;
252 pwm = platform_get_drvdata(pdev);
256 mutex_lock(&pwm_lock);
257 list_del(&pwm->node);
258 mutex_unlock(&pwm_lock);
260 iounmap(pwm->mmio_base);
262 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
263 release_mem_region(r->start, r->end - r->start + 1);
271 static struct platform_driver mxc_pwm_driver = {
275 .probe = mxc_pwm_probe,
276 .remove = __devexit_p(mxc_pwm_remove),
279 static int __init mxc_pwm_init(void)
281 return platform_driver_register(&mxc_pwm_driver);
283 arch_initcall(mxc_pwm_init);
285 static void __exit mxc_pwm_exit(void)
287 platform_driver_unregister(&mxc_pwm_driver);
289 module_exit(mxc_pwm_exit);
291 MODULE_LICENSE("GPL v2");
292 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");