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>
17 #include <linux/delay.h>
19 #include <linux/pwm.h>
21 #include <linux/of_device.h>
23 /* i.MX1 and i.MX21 share the same PWM function block: */
25 #define MX1_PWMC 0x00 /* PWM Control Register */
26 #define MX1_PWMS 0x04 /* PWM Sample Register */
27 #define MX1_PWMP 0x08 /* PWM Period Register */
29 #define MX1_PWMC_EN (1 << 4)
31 /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
33 #define MX3_PWMCR 0x00 /* PWM Control Register */
34 #define MX3_PWMSR 0x04 /* PWM Status Register */
35 #define MX3_PWMSAR 0x0C /* PWM Sample Register */
36 #define MX3_PWMPR 0x10 /* PWM Period Register */
37 #define MX3_PWMCR_PRESCALER(x) ((((x) - 1) & 0xFFF) << 4)
38 #define MX3_PWMCR_DOZEEN (1 << 24)
39 #define MX3_PWMCR_WAITEN (1 << 23)
40 #define MX3_PWMCR_DBGEN (1 << 22)
41 #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
42 #define MX3_PWMCR_CLKSRC_IPG (1 << 16)
43 #define MX3_PWMCR_SWR (1 << 3)
44 #define MX3_PWMCR_EN (1 << 0)
45 #define MX3_PWMSR_FIFOAV_4WORDS 0x4
46 #define MX3_PWMSR_FIFOAV_MASK 0x7
48 #define MX3_PWM_SWR_LOOP 5
53 void __iomem *mmio_base;
57 int (*config)(struct pwm_chip *chip,
58 struct pwm_device *pwm, int duty_ns, int period_ns);
59 void (*set_enable)(struct pwm_chip *chip, bool enable);
62 #define to_imx_chip(chip) container_of(chip, struct imx_chip, chip)
64 static int imx_pwm_config_v1(struct pwm_chip *chip,
65 struct pwm_device *pwm, int duty_ns, int period_ns)
67 struct imx_chip *imx = to_imx_chip(chip);
70 * The PWM subsystem allows for exact frequencies. However,
71 * I cannot connect a scope on my device to the PWM line and
72 * thus cannot provide the program the PWM controller
73 * exactly. Instead, I'm relying on the fact that the
74 * Bootloader (u-boot or WinCE+haret) has programmed the PWM
75 * function group already. So I'll just modify the PWM sample
76 * register to follow the ratio of duty_ns vs. period_ns
79 * This is good enough for programming the brightness of
82 * The real implementation would divide PERCLK[0] first by
83 * both the prescaler (/1 .. /128) and then by CLKSEL
86 u32 max = readl(imx->mmio_base + MX1_PWMP);
87 u32 p = max * duty_ns / period_ns;
88 writel(max - p, imx->mmio_base + MX1_PWMS);
93 static int imx_pwm_enable_v1(struct pwm_chip *chip, struct pwm_device *pwm)
95 struct imx_chip *imx = to_imx_chip(chip);
99 ret = clk_prepare_enable(imx->clk_per);
103 val = readl(imx->mmio_base + MX1_PWMC);
105 writel(val, imx->mmio_base + MX1_PWMC);
110 static void imx_pwm_disable_v1(struct pwm_chip *chip, struct pwm_device *pwm)
112 struct imx_chip *imx = to_imx_chip(chip);
115 val = readl(imx->mmio_base + MX1_PWMC);
117 writel(val, imx->mmio_base + MX1_PWMC);
119 clk_disable_unprepare(imx->clk_per);
122 static void imx_pwm_sw_reset(struct pwm_chip *chip)
124 struct imx_chip *imx = to_imx_chip(chip);
125 struct device *dev = chip->dev;
129 writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR);
131 usleep_range(200, 1000);
132 cr = readl(imx->mmio_base + MX3_PWMCR);
133 } while ((cr & MX3_PWMCR_SWR) &&
134 (wait_count++ < MX3_PWM_SWR_LOOP));
136 if (cr & MX3_PWMCR_SWR)
137 dev_warn(dev, "software reset timeout\n");
141 static int imx_pwm_config_v2(struct pwm_chip *chip,
142 struct pwm_device *pwm, int duty_ns, int period_ns)
144 struct imx_chip *imx = to_imx_chip(chip);
145 struct device *dev = chip->dev;
146 unsigned long long c;
147 unsigned long period_cycles, duty_cycles, prescale;
148 unsigned int period_ms;
149 bool enable = pwm_is_enabled(pwm);
154 * i.MX PWMv2 has a 4-word sample FIFO.
155 * In order to avoid FIFO overflow issue, we do software reset
156 * to clear all sample FIFO if the controller is disabled or
157 * wait for a full PWM cycle to get a relinquished FIFO slot
158 * when the controller is enabled and the FIFO is fully loaded.
161 sr = readl(imx->mmio_base + MX3_PWMSR);
162 fifoav = sr & MX3_PWMSR_FIFOAV_MASK;
163 if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
164 period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
168 sr = readl(imx->mmio_base + MX3_PWMSR);
169 if (fifoav == (sr & MX3_PWMSR_FIFOAV_MASK))
170 dev_warn(dev, "there is no free FIFO slot\n");
173 imx_pwm_sw_reset(chip);
176 c = clk_get_rate(imx->clk_per);
178 do_div(c, 1000000000);
181 prescale = period_cycles / 0x10000 + 1;
183 period_cycles /= prescale;
184 c = (unsigned long long)period_cycles * duty_ns;
185 do_div(c, period_ns);
189 * according to imx pwm RM, the real period value should be
190 * PERIOD value in PWMPR plus 2.
192 if (period_cycles > 2)
197 writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
198 writel(period_cycles, imx->mmio_base + MX3_PWMPR);
200 cr = MX3_PWMCR_PRESCALER(prescale) |
201 MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
202 MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH;
207 writel(cr, imx->mmio_base + MX3_PWMCR);
212 static void imx_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
214 struct imx_chip *imx = to_imx_chip(chip);
217 val = readl(imx->mmio_base + MX3_PWMCR);
222 val &= ~MX3_PWMCR_EN;
224 writel(val, imx->mmio_base + MX3_PWMCR);
227 static int imx_pwm_config(struct pwm_chip *chip,
228 struct pwm_device *pwm, int duty_ns, int period_ns)
230 struct imx_chip *imx = to_imx_chip(chip);
233 ret = clk_prepare_enable(imx->clk_per);
237 ret = imx->config(chip, pwm, duty_ns, period_ns);
239 clk_disable_unprepare(imx->clk_per);
244 static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
246 struct imx_chip *imx = to_imx_chip(chip);
249 ret = clk_prepare_enable(imx->clk_per);
253 imx->set_enable(chip, true);
258 static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
260 struct imx_chip *imx = to_imx_chip(chip);
262 imx->set_enable(chip, false);
264 clk_disable_unprepare(imx->clk_per);
267 static const struct pwm_ops imx_pwm_ops_v1 = {
268 .enable = imx_pwm_enable_v1,
269 .disable = imx_pwm_disable_v1,
270 .config = imx_pwm_config_v1,
271 .owner = THIS_MODULE,
274 static const struct pwm_ops imx_pwm_ops_v2 = {
275 .enable = imx_pwm_enable,
276 .disable = imx_pwm_disable,
277 .config = imx_pwm_config,
278 .owner = THIS_MODULE,
281 struct imx_pwm_data {
282 int (*config)(struct pwm_chip *chip,
283 struct pwm_device *pwm, int duty_ns, int period_ns);
284 void (*set_enable)(struct pwm_chip *chip, bool enable);
285 const struct pwm_ops *ops;
288 static struct imx_pwm_data imx_pwm_data_v1 = {
289 .ops = &imx_pwm_ops_v1,
292 static struct imx_pwm_data imx_pwm_data_v2 = {
293 .config = imx_pwm_config_v2,
294 .set_enable = imx_pwm_set_enable_v2,
295 .ops = &imx_pwm_ops_v2,
298 static const struct of_device_id imx_pwm_dt_ids[] = {
299 { .compatible = "fsl,imx1-pwm", .data = &imx_pwm_data_v1, },
300 { .compatible = "fsl,imx27-pwm", .data = &imx_pwm_data_v2, },
303 MODULE_DEVICE_TABLE(of, imx_pwm_dt_ids);
305 static int imx_pwm_probe(struct platform_device *pdev)
307 const struct of_device_id *of_id =
308 of_match_device(imx_pwm_dt_ids, &pdev->dev);
309 const struct imx_pwm_data *data;
310 struct imx_chip *imx;
319 imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
323 imx->clk_per = devm_clk_get(&pdev->dev, "per");
324 if (IS_ERR(imx->clk_per)) {
325 dev_err(&pdev->dev, "getting per clock failed with %ld\n",
326 PTR_ERR(imx->clk_per));
327 return PTR_ERR(imx->clk_per);
330 imx->chip.ops = data->ops;
331 imx->chip.dev = &pdev->dev;
334 imx->chip.can_sleep = true;
336 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
337 imx->mmio_base = devm_ioremap_resource(&pdev->dev, r);
338 if (IS_ERR(imx->mmio_base))
339 return PTR_ERR(imx->mmio_base);
341 imx->config = data->config;
342 imx->set_enable = data->set_enable;
344 ret = pwmchip_add(&imx->chip);
348 platform_set_drvdata(pdev, imx);
352 static int imx_pwm_remove(struct platform_device *pdev)
354 struct imx_chip *imx;
356 imx = platform_get_drvdata(pdev);
360 return pwmchip_remove(&imx->chip);
363 static struct platform_driver imx_pwm_driver = {
366 .of_match_table = imx_pwm_dt_ids,
368 .probe = imx_pwm_probe,
369 .remove = imx_pwm_remove,
372 module_platform_driver(imx_pwm_driver);
374 MODULE_LICENSE("GPL v2");
375 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");