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1 | /* | |
2 | * simple driver for PWM (Pulse Width Modulator) controller | |
3 | * | |
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. | |
7 | * | |
8 | * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com> | |
9 | */ | |
10 | ||
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/io.h> | |
18 | #include <linux/pwm.h> | |
19 | #include <linux/of.h> | |
20 | #include <linux/of_device.h> | |
21 | ||
22 | /* i.MX1 and i.MX21 share the same PWM function block: */ | |
23 | ||
24 | #define MX1_PWMC 0x00 /* PWM Control Register */ | |
25 | #define MX1_PWMS 0x04 /* PWM Sample Register */ | |
26 | #define MX1_PWMP 0x08 /* PWM Period Register */ | |
27 | ||
28 | #define MX1_PWMC_EN (1 << 4) | |
29 | ||
30 | /* i.MX27, i.MX31, i.MX35 share the same PWM function block: */ | |
31 | ||
32 | #define MX3_PWMCR 0x00 /* PWM Control Register */ | |
33 | #define MX3_PWMSAR 0x0C /* PWM Sample Register */ | |
34 | #define MX3_PWMPR 0x10 /* PWM Period Register */ | |
35 | #define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4) | |
36 | #define MX3_PWMCR_DOZEEN (1 << 24) | |
37 | #define MX3_PWMCR_WAITEN (1 << 23) | |
38 | #define MX3_PWMCR_DBGEN (1 << 22) | |
39 | #define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16) | |
40 | #define MX3_PWMCR_CLKSRC_IPG (1 << 16) | |
41 | #define MX3_PWMCR_EN (1 << 0) | |
42 | ||
43 | struct imx_chip { | |
44 | struct clk *clk_per; | |
45 | struct clk *clk_ipg; | |
46 | ||
47 | void __iomem *mmio_base; | |
48 | ||
49 | struct pwm_chip chip; | |
50 | ||
51 | int (*config)(struct pwm_chip *chip, | |
52 | struct pwm_device *pwm, int duty_ns, int period_ns); | |
53 | void (*set_enable)(struct pwm_chip *chip, bool enable); | |
54 | }; | |
55 | ||
56 | #define to_imx_chip(chip) container_of(chip, struct imx_chip, chip) | |
57 | ||
58 | static int imx_pwm_config_v1(struct pwm_chip *chip, | |
59 | struct pwm_device *pwm, int duty_ns, int period_ns) | |
60 | { | |
61 | struct imx_chip *imx = to_imx_chip(chip); | |
62 | ||
63 | /* | |
64 | * The PWM subsystem allows for exact frequencies. However, | |
65 | * I cannot connect a scope on my device to the PWM line and | |
66 | * thus cannot provide the program the PWM controller | |
67 | * exactly. Instead, I'm relying on the fact that the | |
68 | * Bootloader (u-boot or WinCE+haret) has programmed the PWM | |
69 | * function group already. So I'll just modify the PWM sample | |
70 | * register to follow the ratio of duty_ns vs. period_ns | |
71 | * accordingly. | |
72 | * | |
73 | * This is good enough for programming the brightness of | |
74 | * the LCD backlight. | |
75 | * | |
76 | * The real implementation would divide PERCLK[0] first by | |
77 | * both the prescaler (/1 .. /128) and then by CLKSEL | |
78 | * (/2 .. /16). | |
79 | */ | |
80 | u32 max = readl(imx->mmio_base + MX1_PWMP); | |
81 | u32 p = max * duty_ns / period_ns; | |
82 | writel(max - p, imx->mmio_base + MX1_PWMS); | |
83 | ||
84 | return 0; | |
85 | } | |
86 | ||
87 | static void imx_pwm_set_enable_v1(struct pwm_chip *chip, bool enable) | |
88 | { | |
89 | struct imx_chip *imx = to_imx_chip(chip); | |
90 | u32 val; | |
91 | ||
92 | val = readl(imx->mmio_base + MX1_PWMC); | |
93 | ||
94 | if (enable) | |
95 | val |= MX1_PWMC_EN; | |
96 | else | |
97 | val &= ~MX1_PWMC_EN; | |
98 | ||
99 | writel(val, imx->mmio_base + MX1_PWMC); | |
100 | } | |
101 | ||
102 | static int imx_pwm_config_v2(struct pwm_chip *chip, | |
103 | struct pwm_device *pwm, int duty_ns, int period_ns) | |
104 | { | |
105 | struct imx_chip *imx = to_imx_chip(chip); | |
106 | unsigned long long c; | |
107 | unsigned long period_cycles, duty_cycles, prescale; | |
108 | u32 cr; | |
109 | ||
110 | c = clk_get_rate(imx->clk_per); | |
111 | c = c * period_ns; | |
112 | do_div(c, 1000000000); | |
113 | period_cycles = c; | |
114 | ||
115 | prescale = period_cycles / 0x10000 + 1; | |
116 | ||
117 | period_cycles /= prescale; | |
118 | c = (unsigned long long)period_cycles * duty_ns; | |
119 | do_div(c, period_ns); | |
120 | duty_cycles = c; | |
121 | ||
122 | /* | |
123 | * according to imx pwm RM, the real period value should be | |
124 | * PERIOD value in PWMPR plus 2. | |
125 | */ | |
126 | if (period_cycles > 2) | |
127 | period_cycles -= 2; | |
128 | else | |
129 | period_cycles = 0; | |
130 | ||
131 | writel(duty_cycles, imx->mmio_base + MX3_PWMSAR); | |
132 | writel(period_cycles, imx->mmio_base + MX3_PWMPR); | |
133 | ||
134 | cr = MX3_PWMCR_PRESCALER(prescale) | | |
135 | MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN | | |
136 | MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH; | |
137 | ||
138 | if (test_bit(PWMF_ENABLED, &pwm->flags)) | |
139 | cr |= MX3_PWMCR_EN; | |
140 | ||
141 | writel(cr, imx->mmio_base + MX3_PWMCR); | |
142 | ||
143 | return 0; | |
144 | } | |
145 | ||
146 | static void imx_pwm_set_enable_v2(struct pwm_chip *chip, bool enable) | |
147 | { | |
148 | struct imx_chip *imx = to_imx_chip(chip); | |
149 | u32 val; | |
150 | ||
151 | val = readl(imx->mmio_base + MX3_PWMCR); | |
152 | ||
153 | if (enable) | |
154 | val |= MX3_PWMCR_EN; | |
155 | else | |
156 | val &= ~MX3_PWMCR_EN; | |
157 | ||
158 | writel(val, imx->mmio_base + MX3_PWMCR); | |
159 | } | |
160 | ||
161 | static int imx_pwm_config(struct pwm_chip *chip, | |
162 | struct pwm_device *pwm, int duty_ns, int period_ns) | |
163 | { | |
164 | struct imx_chip *imx = to_imx_chip(chip); | |
165 | int ret; | |
166 | ||
167 | ret = clk_prepare_enable(imx->clk_ipg); | |
168 | if (ret) | |
169 | return ret; | |
170 | ||
171 | ret = imx->config(chip, pwm, duty_ns, period_ns); | |
172 | ||
173 | clk_disable_unprepare(imx->clk_ipg); | |
174 | ||
175 | return ret; | |
176 | } | |
177 | ||
178 | static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) | |
179 | { | |
180 | struct imx_chip *imx = to_imx_chip(chip); | |
181 | int ret; | |
182 | ||
183 | ret = clk_prepare_enable(imx->clk_per); | |
184 | if (ret) | |
185 | return ret; | |
186 | ||
187 | imx->set_enable(chip, true); | |
188 | ||
189 | return 0; | |
190 | } | |
191 | ||
192 | static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) | |
193 | { | |
194 | struct imx_chip *imx = to_imx_chip(chip); | |
195 | ||
196 | imx->set_enable(chip, false); | |
197 | ||
198 | clk_disable_unprepare(imx->clk_per); | |
199 | } | |
200 | ||
201 | static struct pwm_ops imx_pwm_ops = { | |
202 | .enable = imx_pwm_enable, | |
203 | .disable = imx_pwm_disable, | |
204 | .config = imx_pwm_config, | |
205 | .owner = THIS_MODULE, | |
206 | }; | |
207 | ||
208 | struct imx_pwm_data { | |
209 | int (*config)(struct pwm_chip *chip, | |
210 | struct pwm_device *pwm, int duty_ns, int period_ns); | |
211 | void (*set_enable)(struct pwm_chip *chip, bool enable); | |
212 | }; | |
213 | ||
214 | static struct imx_pwm_data imx_pwm_data_v1 = { | |
215 | .config = imx_pwm_config_v1, | |
216 | .set_enable = imx_pwm_set_enable_v1, | |
217 | }; | |
218 | ||
219 | static struct imx_pwm_data imx_pwm_data_v2 = { | |
220 | .config = imx_pwm_config_v2, | |
221 | .set_enable = imx_pwm_set_enable_v2, | |
222 | }; | |
223 | ||
224 | static const struct of_device_id imx_pwm_dt_ids[] = { | |
225 | { .compatible = "fsl,imx1-pwm", .data = &imx_pwm_data_v1, }, | |
226 | { .compatible = "fsl,imx27-pwm", .data = &imx_pwm_data_v2, }, | |
227 | { /* sentinel */ } | |
228 | }; | |
229 | MODULE_DEVICE_TABLE(of, imx_pwm_dt_ids); | |
230 | ||
231 | static int imx_pwm_probe(struct platform_device *pdev) | |
232 | { | |
233 | const struct of_device_id *of_id = | |
234 | of_match_device(imx_pwm_dt_ids, &pdev->dev); | |
235 | const struct imx_pwm_data *data; | |
236 | struct imx_chip *imx; | |
237 | struct resource *r; | |
238 | int ret = 0; | |
239 | ||
240 | if (!of_id) | |
241 | return -ENODEV; | |
242 | ||
243 | imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL); | |
244 | if (imx == NULL) | |
245 | return -ENOMEM; | |
246 | ||
247 | imx->clk_per = devm_clk_get(&pdev->dev, "per"); | |
248 | if (IS_ERR(imx->clk_per)) { | |
249 | dev_err(&pdev->dev, "getting per clock failed with %ld\n", | |
250 | PTR_ERR(imx->clk_per)); | |
251 | return PTR_ERR(imx->clk_per); | |
252 | } | |
253 | ||
254 | imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg"); | |
255 | if (IS_ERR(imx->clk_ipg)) { | |
256 | dev_err(&pdev->dev, "getting ipg clock failed with %ld\n", | |
257 | PTR_ERR(imx->clk_ipg)); | |
258 | return PTR_ERR(imx->clk_ipg); | |
259 | } | |
260 | ||
261 | imx->chip.ops = &imx_pwm_ops; | |
262 | imx->chip.dev = &pdev->dev; | |
263 | imx->chip.base = -1; | |
264 | imx->chip.npwm = 1; | |
265 | ||
266 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
267 | imx->mmio_base = devm_ioremap_resource(&pdev->dev, r); | |
268 | if (IS_ERR(imx->mmio_base)) | |
269 | return PTR_ERR(imx->mmio_base); | |
270 | ||
271 | data = of_id->data; | |
272 | imx->config = data->config; | |
273 | imx->set_enable = data->set_enable; | |
274 | ||
275 | ret = pwmchip_add(&imx->chip); | |
276 | if (ret < 0) | |
277 | return ret; | |
278 | ||
279 | platform_set_drvdata(pdev, imx); | |
280 | return 0; | |
281 | } | |
282 | ||
283 | static int imx_pwm_remove(struct platform_device *pdev) | |
284 | { | |
285 | struct imx_chip *imx; | |
286 | ||
287 | imx = platform_get_drvdata(pdev); | |
288 | if (imx == NULL) | |
289 | return -ENODEV; | |
290 | ||
291 | return pwmchip_remove(&imx->chip); | |
292 | } | |
293 | ||
294 | static struct platform_driver imx_pwm_driver = { | |
295 | .driver = { | |
296 | .name = "imx-pwm", | |
297 | .owner = THIS_MODULE, | |
298 | .of_match_table = imx_pwm_dt_ids, | |
299 | }, | |
300 | .probe = imx_pwm_probe, | |
301 | .remove = imx_pwm_remove, | |
302 | }; | |
303 | ||
304 | module_platform_driver(imx_pwm_driver); | |
305 | ||
306 | MODULE_LICENSE("GPL v2"); | |
307 | MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>"); |