1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2017 Sanechips Technology Co., Ltd.
4 * Copyright 2017 Linaro Ltd.
5 */
6
7 #include <linux/clk.h>
8 #include <linux/err.h>
9 #include <linux/io.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/platform_device.h>
13 #include <linux/pwm.h>
14 #include <linux/slab.h>
15
16 #define ZX_PWM_MODE 0x0
17 #define ZX_PWM_CLKDIV_SHIFT 2
18 #define ZX_PWM_CLKDIV_MASK GENMASK(11, 2)
19 #define ZX_PWM_CLKDIV(x) (((x) << ZX_PWM_CLKDIV_SHIFT) & \
20 ZX_PWM_CLKDIV_MASK)
21 #define ZX_PWM_POLAR BIT(1)
22 #define ZX_PWM_EN BIT(0)
23 #define ZX_PWM_PERIOD 0x4
24 #define ZX_PWM_DUTY 0x8
25
26 #define ZX_PWM_CLKDIV_MAX 1023
27 #define ZX_PWM_PERIOD_MAX 65535
28
29 struct zx_pwm_chip {
30 struct pwm_chip chip;
31 struct clk *pclk;
32 struct clk *wclk;
33 void __iomem *base;
34 };
35
to_zx_pwm_chip(struct pwm_chip * chip)36 static inline struct zx_pwm_chip *to_zx_pwm_chip(struct pwm_chip *chip)
37 {
38 return container_of(chip, struct zx_pwm_chip, chip);
39 }
40
zx_pwm_readl(struct zx_pwm_chip * zpc,unsigned int hwpwm,unsigned int offset)41 static inline u32 zx_pwm_readl(struct zx_pwm_chip *zpc, unsigned int hwpwm,
42 unsigned int offset)
43 {
44 return readl(zpc->base + (hwpwm + 1) * 0x10 + offset);
45 }
46
zx_pwm_writel(struct zx_pwm_chip * zpc,unsigned int hwpwm,unsigned int offset,u32 value)47 static inline void zx_pwm_writel(struct zx_pwm_chip *zpc, unsigned int hwpwm,
48 unsigned int offset, u32 value)
49 {
50 writel(value, zpc->base + (hwpwm + 1) * 0x10 + offset);
51 }
52
zx_pwm_set_mask(struct zx_pwm_chip * zpc,unsigned int hwpwm,unsigned int offset,u32 mask,u32 value)53 static void zx_pwm_set_mask(struct zx_pwm_chip *zpc, unsigned int hwpwm,
54 unsigned int offset, u32 mask, u32 value)
55 {
56 u32 data;
57
58 data = zx_pwm_readl(zpc, hwpwm, offset);
59 data &= ~mask;
60 data |= value & mask;
61 zx_pwm_writel(zpc, hwpwm, offset, data);
62 }
63
zx_pwm_get_state(struct pwm_chip * chip,struct pwm_device * pwm,struct pwm_state * state)64 static void zx_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
65 struct pwm_state *state)
66 {
67 struct zx_pwm_chip *zpc = to_zx_pwm_chip(chip);
68 unsigned long rate;
69 unsigned int div;
70 u32 value;
71 u64 tmp;
72
73 value = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_MODE);
74
75 if (value & ZX_PWM_POLAR)
76 state->polarity = PWM_POLARITY_NORMAL;
77 else
78 state->polarity = PWM_POLARITY_INVERSED;
79
80 if (value & ZX_PWM_EN)
81 state->enabled = true;
82 else
83 state->enabled = false;
84
85 div = (value & ZX_PWM_CLKDIV_MASK) >> ZX_PWM_CLKDIV_SHIFT;
86 rate = clk_get_rate(zpc->wclk);
87
88 tmp = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_PERIOD);
89 tmp *= div * NSEC_PER_SEC;
90 state->period = DIV_ROUND_CLOSEST_ULL(tmp, rate);
91
92 tmp = zx_pwm_readl(zpc, pwm->hwpwm, ZX_PWM_DUTY);
93 tmp *= div * NSEC_PER_SEC;
94 state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, rate);
95 }
96
zx_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,unsigned int duty_ns,unsigned int period_ns)97 static int zx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
98 unsigned int duty_ns, unsigned int period_ns)
99 {
100 struct zx_pwm_chip *zpc = to_zx_pwm_chip(chip);
101 unsigned int period_cycles, duty_cycles;
102 unsigned long long c;
103 unsigned int div = 1;
104 unsigned long rate;
105
106 /* Find out the best divider */
107 rate = clk_get_rate(zpc->wclk);
108
109 while (1) {
110 c = rate / div;
111 c = c * period_ns;
112 do_div(c, NSEC_PER_SEC);
113
114 if (c < ZX_PWM_PERIOD_MAX)
115 break;
116
117 div++;
118
119 if (div > ZX_PWM_CLKDIV_MAX)
120 return -ERANGE;
121 }
122
123 /* Calculate duty cycles */
124 period_cycles = c;
125 c *= duty_ns;
126 do_div(c, period_ns);
127 duty_cycles = c;
128
129 /*
130 * If the PWM is being enabled, we have to temporarily disable it
131 * before configuring the registers.
132 */
133 if (pwm_is_enabled(pwm))
134 zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE, ZX_PWM_EN, 0);
135
136 /* Set up registers */
137 zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE, ZX_PWM_CLKDIV_MASK,
138 ZX_PWM_CLKDIV(div));
139 zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_PERIOD, period_cycles);
140 zx_pwm_writel(zpc, pwm->hwpwm, ZX_PWM_DUTY, duty_cycles);
141
142 /* Re-enable the PWM if needed */
143 if (pwm_is_enabled(pwm))
144 zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE,
145 ZX_PWM_EN, ZX_PWM_EN);
146
147 return 0;
148 }
149
zx_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)150 static int zx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
151 const struct pwm_state *state)
152 {
153 struct zx_pwm_chip *zpc = to_zx_pwm_chip(chip);
154 struct pwm_state cstate;
155 int ret;
156
157 pwm_get_state(pwm, &cstate);
158
159 if (state->polarity != cstate.polarity)
160 zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE, ZX_PWM_POLAR,
161 (state->polarity == PWM_POLARITY_INVERSED) ?
162 0 : ZX_PWM_POLAR);
163
164 if (state->period != cstate.period ||
165 state->duty_cycle != cstate.duty_cycle) {
166 ret = zx_pwm_config(chip, pwm, state->duty_cycle,
167 state->period);
168 if (ret)
169 return ret;
170 }
171
172 if (state->enabled != cstate.enabled) {
173 if (state->enabled) {
174 ret = clk_prepare_enable(zpc->wclk);
175 if (ret)
176 return ret;
177
178 zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE,
179 ZX_PWM_EN, ZX_PWM_EN);
180 } else {
181 zx_pwm_set_mask(zpc, pwm->hwpwm, ZX_PWM_MODE,
182 ZX_PWM_EN, 0);
183 clk_disable_unprepare(zpc->wclk);
184 }
185 }
186
187 return 0;
188 }
189
190 static const struct pwm_ops zx_pwm_ops = {
191 .apply = zx_pwm_apply,
192 .get_state = zx_pwm_get_state,
193 .owner = THIS_MODULE,
194 };
195
zx_pwm_probe(struct platform_device * pdev)196 static int zx_pwm_probe(struct platform_device *pdev)
197 {
198 struct zx_pwm_chip *zpc;
199 struct resource *res;
200 unsigned int i;
201 int ret;
202
203 zpc = devm_kzalloc(&pdev->dev, sizeof(*zpc), GFP_KERNEL);
204 if (!zpc)
205 return -ENOMEM;
206
207 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
208 zpc->base = devm_ioremap_resource(&pdev->dev, res);
209 if (IS_ERR(zpc->base))
210 return PTR_ERR(zpc->base);
211
212 zpc->pclk = devm_clk_get(&pdev->dev, "pclk");
213 if (IS_ERR(zpc->pclk))
214 return PTR_ERR(zpc->pclk);
215
216 zpc->wclk = devm_clk_get(&pdev->dev, "wclk");
217 if (IS_ERR(zpc->wclk))
218 return PTR_ERR(zpc->wclk);
219
220 ret = clk_prepare_enable(zpc->pclk);
221 if (ret)
222 return ret;
223
224 zpc->chip.dev = &pdev->dev;
225 zpc->chip.ops = &zx_pwm_ops;
226 zpc->chip.base = -1;
227 zpc->chip.npwm = 4;
228 zpc->chip.of_xlate = of_pwm_xlate_with_flags;
229 zpc->chip.of_pwm_n_cells = 3;
230
231 /*
232 * PWM devices may be enabled by firmware, and let's disable all of
233 * them initially to save power.
234 */
235 for (i = 0; i < zpc->chip.npwm; i++)
236 zx_pwm_set_mask(zpc, i, ZX_PWM_MODE, ZX_PWM_EN, 0);
237
238 ret = pwmchip_add(&zpc->chip);
239 if (ret < 0) {
240 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
241 clk_disable_unprepare(zpc->pclk);
242 return ret;
243 }
244
245 platform_set_drvdata(pdev, zpc);
246
247 return 0;
248 }
249
zx_pwm_remove(struct platform_device * pdev)250 static int zx_pwm_remove(struct platform_device *pdev)
251 {
252 struct zx_pwm_chip *zpc = platform_get_drvdata(pdev);
253 int ret;
254
255 ret = pwmchip_remove(&zpc->chip);
256 clk_disable_unprepare(zpc->pclk);
257
258 return ret;
259 }
260
261 static const struct of_device_id zx_pwm_dt_ids[] = {
262 { .compatible = "zte,zx296718-pwm", },
263 { /* sentinel */ }
264 };
265 MODULE_DEVICE_TABLE(of, zx_pwm_dt_ids);
266
267 static struct platform_driver zx_pwm_driver = {
268 .driver = {
269 .name = "zx-pwm",
270 .of_match_table = zx_pwm_dt_ids,
271 },
272 .probe = zx_pwm_probe,
273 .remove = zx_pwm_remove,
274 };
275 module_platform_driver(zx_pwm_driver);
276
277 MODULE_ALIAS("platform:zx-pwm");
278 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
279 MODULE_DESCRIPTION("ZTE ZX PWM Driver");
280 MODULE_LICENSE("GPL v2");
281