1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2019 Spreadtrum Communications Inc.
4 */
5
6 #include <linux/clk.h>
7 #include <linux/err.h>
8 #include <linux/io.h>
9 #include <linux/math64.h>
10 #include <linux/mod_devicetable.h>
11 #include <linux/module.h>
12 #include <linux/platform_device.h>
13 #include <linux/pwm.h>
14
15 #define SPRD_PWM_PRESCALE 0x0
16 #define SPRD_PWM_MOD 0x4
17 #define SPRD_PWM_DUTY 0x8
18 #define SPRD_PWM_ENABLE 0x18
19
20 #define SPRD_PWM_MOD_MAX GENMASK(7, 0)
21 #define SPRD_PWM_DUTY_MSK GENMASK(15, 0)
22 #define SPRD_PWM_PRESCALE_MSK GENMASK(7, 0)
23 #define SPRD_PWM_ENABLE_BIT BIT(0)
24
25 #define SPRD_PWM_CHN_NUM 4
26 #define SPRD_PWM_REGS_SHIFT 5
27 #define SPRD_PWM_CHN_CLKS_NUM 2
28 #define SPRD_PWM_CHN_OUTPUT_CLK 1
29
30 struct sprd_pwm_chn {
31 struct clk_bulk_data clks[SPRD_PWM_CHN_CLKS_NUM];
32 u32 clk_rate;
33 };
34
35 struct sprd_pwm_chip {
36 void __iomem *base;
37 struct sprd_pwm_chn chn[SPRD_PWM_CHN_NUM];
38 };
39
sprd_pwm_from_chip(struct pwm_chip * chip)40 static inline struct sprd_pwm_chip* sprd_pwm_from_chip(struct pwm_chip *chip)
41 {
42 return pwmchip_get_drvdata(chip);
43 }
44
45 /*
46 * The list of clocks required by PWM channels, and each channel has 2 clocks:
47 * enable clock and pwm clock.
48 */
49 static const char * const sprd_pwm_clks[] = {
50 "enable0", "pwm0",
51 "enable1", "pwm1",
52 "enable2", "pwm2",
53 "enable3", "pwm3",
54 };
55
sprd_pwm_read(struct sprd_pwm_chip * spc,u32 hwid,u32 reg)56 static u32 sprd_pwm_read(struct sprd_pwm_chip *spc, u32 hwid, u32 reg)
57 {
58 u32 offset = reg + (hwid << SPRD_PWM_REGS_SHIFT);
59
60 return readl_relaxed(spc->base + offset);
61 }
62
sprd_pwm_write(struct sprd_pwm_chip * spc,u32 hwid,u32 reg,u32 val)63 static void sprd_pwm_write(struct sprd_pwm_chip *spc, u32 hwid,
64 u32 reg, u32 val)
65 {
66 u32 offset = reg + (hwid << SPRD_PWM_REGS_SHIFT);
67
68 writel_relaxed(val, spc->base + offset);
69 }
70
sprd_pwm_get_state(struct pwm_chip * chip,struct pwm_device * pwm,struct pwm_state * state)71 static int sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
72 struct pwm_state *state)
73 {
74 struct sprd_pwm_chip *spc = sprd_pwm_from_chip(chip);
75 struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm];
76 u32 val, duty, prescale;
77 u64 tmp;
78 int ret;
79
80 /*
81 * The clocks to PWM channel has to be enabled first before
82 * reading to the registers.
83 */
84 ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM, chn->clks);
85 if (ret) {
86 dev_err(pwmchip_parent(chip), "failed to enable pwm%u clocks\n",
87 pwm->hwpwm);
88 return ret;
89 }
90
91 val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_ENABLE);
92 if (val & SPRD_PWM_ENABLE_BIT)
93 state->enabled = true;
94 else
95 state->enabled = false;
96
97 /*
98 * The hardware provides a counter that is feed by the source clock.
99 * The period length is (PRESCALE + 1) * MOD counter steps.
100 * The duty cycle length is (PRESCALE + 1) * DUTY counter steps.
101 * Thus the period_ns and duty_ns calculation formula should be:
102 * period_ns = NSEC_PER_SEC * (prescale + 1) * mod / clk_rate
103 * duty_ns = NSEC_PER_SEC * (prescale + 1) * duty / clk_rate
104 */
105 val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_PRESCALE);
106 prescale = val & SPRD_PWM_PRESCALE_MSK;
107 tmp = (prescale + 1) * NSEC_PER_SEC * SPRD_PWM_MOD_MAX;
108 state->period = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate);
109
110 val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_DUTY);
111 duty = val & SPRD_PWM_DUTY_MSK;
112 tmp = (prescale + 1) * NSEC_PER_SEC * duty;
113 state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate);
114 state->polarity = PWM_POLARITY_NORMAL;
115
116 /* Disable PWM clocks if the PWM channel is not in enable state. */
117 if (!state->enabled)
118 clk_bulk_disable_unprepare(SPRD_PWM_CHN_CLKS_NUM, chn->clks);
119
120 return 0;
121 }
122
sprd_pwm_config(struct sprd_pwm_chip * spc,struct pwm_device * pwm,int duty_ns,int period_ns)123 static int sprd_pwm_config(struct sprd_pwm_chip *spc, struct pwm_device *pwm,
124 int duty_ns, int period_ns)
125 {
126 struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm];
127 u32 prescale, duty;
128 u64 tmp;
129
130 /*
131 * The hardware provides a counter that is feed by the source clock.
132 * The period length is (PRESCALE + 1) * MOD counter steps.
133 * The duty cycle length is (PRESCALE + 1) * DUTY counter steps.
134 *
135 * To keep the maths simple we're always using MOD = SPRD_PWM_MOD_MAX.
136 * The value for PRESCALE is selected such that the resulting period
137 * gets the maximal length not bigger than the requested one with the
138 * given settings (MOD = SPRD_PWM_MOD_MAX and input clock).
139 */
140 duty = duty_ns * SPRD_PWM_MOD_MAX / period_ns;
141
142 tmp = (u64)chn->clk_rate * period_ns;
143 do_div(tmp, NSEC_PER_SEC);
144 prescale = DIV_ROUND_CLOSEST_ULL(tmp, SPRD_PWM_MOD_MAX) - 1;
145 if (prescale > SPRD_PWM_PRESCALE_MSK)
146 prescale = SPRD_PWM_PRESCALE_MSK;
147
148 /*
149 * Note: Writing DUTY triggers the hardware to actually apply the
150 * values written to MOD and DUTY to the output, so must keep writing
151 * DUTY last.
152 *
153 * The hardware can ensures that current running period is completed
154 * before changing a new configuration to avoid mixed settings.
155 */
156 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_PRESCALE, prescale);
157 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_MOD, SPRD_PWM_MOD_MAX);
158 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_DUTY, duty);
159
160 return 0;
161 }
162
sprd_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)163 static int sprd_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
164 const struct pwm_state *state)
165 {
166 struct sprd_pwm_chip *spc = sprd_pwm_from_chip(chip);
167 struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm];
168 struct pwm_state *cstate = &pwm->state;
169 int ret;
170
171 if (state->polarity != PWM_POLARITY_NORMAL)
172 return -EINVAL;
173
174 if (state->enabled) {
175 if (!cstate->enabled) {
176 /*
177 * The clocks to PWM channel has to be enabled first
178 * before writing to the registers.
179 */
180 ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM,
181 chn->clks);
182 if (ret) {
183 dev_err(pwmchip_parent(chip),
184 "failed to enable pwm%u clocks\n",
185 pwm->hwpwm);
186 return ret;
187 }
188 }
189
190 ret = sprd_pwm_config(spc, pwm, state->duty_cycle,
191 state->period);
192 if (ret)
193 return ret;
194
195 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_ENABLE, 1);
196 } else if (cstate->enabled) {
197 /*
198 * Note: After setting SPRD_PWM_ENABLE to zero, the controller
199 * will not wait for current period to be completed, instead it
200 * will stop the PWM channel immediately.
201 */
202 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_ENABLE, 0);
203
204 clk_bulk_disable_unprepare(SPRD_PWM_CHN_CLKS_NUM, chn->clks);
205 }
206
207 return 0;
208 }
209
210 static const struct pwm_ops sprd_pwm_ops = {
211 .apply = sprd_pwm_apply,
212 .get_state = sprd_pwm_get_state,
213 };
214
sprd_pwm_clk_init(struct device * dev,struct sprd_pwm_chn chn[SPRD_PWM_CHN_NUM])215 static int sprd_pwm_clk_init(struct device *dev,
216 struct sprd_pwm_chn chn[SPRD_PWM_CHN_NUM])
217 {
218 struct clk *clk_pwm;
219 int ret, i;
220
221 for (i = 0; i < SPRD_PWM_CHN_NUM; i++) {
222 int j;
223
224 for (j = 0; j < SPRD_PWM_CHN_CLKS_NUM; ++j)
225 chn[i].clks[j].id =
226 sprd_pwm_clks[i * SPRD_PWM_CHN_CLKS_NUM + j];
227
228 ret = devm_clk_bulk_get(dev, SPRD_PWM_CHN_CLKS_NUM,
229 chn[i].clks);
230 if (ret) {
231 if (ret == -ENOENT)
232 break;
233
234 return dev_err_probe(dev, ret,
235 "failed to get channel clocks\n");
236 }
237
238 clk_pwm = chn[i].clks[SPRD_PWM_CHN_OUTPUT_CLK].clk;
239 chn[i].clk_rate = clk_get_rate(clk_pwm);
240 }
241
242 if (!i)
243 return dev_err_probe(dev, -ENODEV, "no available PWM channels\n");
244
245 return i;
246 }
247
sprd_pwm_probe(struct platform_device * pdev)248 static int sprd_pwm_probe(struct platform_device *pdev)
249 {
250 struct pwm_chip *chip;
251 struct sprd_pwm_chip *spc;
252 struct sprd_pwm_chn chn[SPRD_PWM_CHN_NUM];
253 int ret, npwm;
254
255 npwm = sprd_pwm_clk_init(&pdev->dev, chn);
256 if (npwm < 0)
257 return npwm;
258
259 chip = devm_pwmchip_alloc(&pdev->dev, npwm, sizeof(*spc));
260 if (IS_ERR(chip))
261 return PTR_ERR(chip);
262 spc = sprd_pwm_from_chip(chip);
263
264 spc->base = devm_platform_ioremap_resource(pdev, 0);
265 if (IS_ERR(spc->base))
266 return PTR_ERR(spc->base);
267
268 memcpy(spc->chn, chn, sizeof(chn));
269
270 chip->ops = &sprd_pwm_ops;
271
272 ret = devm_pwmchip_add(&pdev->dev, chip);
273 if (ret)
274 dev_err(&pdev->dev, "failed to add PWM chip\n");
275
276 return ret;
277 }
278
279 static const struct of_device_id sprd_pwm_of_match[] = {
280 { .compatible = "sprd,ums512-pwm", },
281 { },
282 };
283 MODULE_DEVICE_TABLE(of, sprd_pwm_of_match);
284
285 static struct platform_driver sprd_pwm_driver = {
286 .driver = {
287 .name = "sprd-pwm",
288 .of_match_table = sprd_pwm_of_match,
289 },
290 .probe = sprd_pwm_probe,
291 };
292
293 module_platform_driver(sprd_pwm_driver);
294
295 MODULE_DESCRIPTION("Spreadtrum PWM Driver");
296 MODULE_LICENSE("GPL v2");
297