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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
30struct sprd_pwm_chn {
31 struct clk_bulk_data clks[SPRD_PWM_CHN_CLKS_NUM];
32 u32 clk_rate;
33};
34
35struct sprd_pwm_chip {
36 void __iomem *base;
37 struct device *dev;
38 struct pwm_chip chip;
39 int num_pwms;
40 struct sprd_pwm_chn chn[SPRD_PWM_CHN_NUM];
41};
42
43static inline struct sprd_pwm_chip* sprd_pwm_from_chip(struct pwm_chip *chip)
44{
45 return container_of(chip, struct sprd_pwm_chip, chip);
46}
47
48/*
49 * The list of clocks required by PWM channels, and each channel has 2 clocks:
50 * enable clock and pwm clock.
51 */
52static const char * const sprd_pwm_clks[] = {
53 "enable0", "pwm0",
54 "enable1", "pwm1",
55 "enable2", "pwm2",
56 "enable3", "pwm3",
57};
58
59static u32 sprd_pwm_read(struct sprd_pwm_chip *spc, u32 hwid, u32 reg)
60{
61 u32 offset = reg + (hwid << SPRD_PWM_REGS_SHIFT);
62
63 return readl_relaxed(spc->base + offset);
64}
65
66static void sprd_pwm_write(struct sprd_pwm_chip *spc, u32 hwid,
67 u32 reg, u32 val)
68{
69 u32 offset = reg + (hwid << SPRD_PWM_REGS_SHIFT);
70
71 writel_relaxed(val, spc->base + offset);
72}
73
74static int sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
75 struct pwm_state *state)
76{
77 struct sprd_pwm_chip *spc = sprd_pwm_from_chip(chip);
78 struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm];
79 u32 val, duty, prescale;
80 u64 tmp;
81 int ret;
82
83 /*
84 * The clocks to PWM channel has to be enabled first before
85 * reading to the registers.
86 */
87 ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM, chn->clks);
88 if (ret) {
89 dev_err(spc->dev, "failed to enable pwm%u clocks\n",
90 pwm->hwpwm);
91 return ret;
92 }
93
94 val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_ENABLE);
95 if (val & SPRD_PWM_ENABLE_BIT)
96 state->enabled = true;
97 else
98 state->enabled = false;
99
100 /*
101 * The hardware provides a counter that is feed by the source clock.
102 * The period length is (PRESCALE + 1) * MOD counter steps.
103 * The duty cycle length is (PRESCALE + 1) * DUTY counter steps.
104 * Thus the period_ns and duty_ns calculation formula should be:
105 * period_ns = NSEC_PER_SEC * (prescale + 1) * mod / clk_rate
106 * duty_ns = NSEC_PER_SEC * (prescale + 1) * duty / clk_rate
107 */
108 val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_PRESCALE);
109 prescale = val & SPRD_PWM_PRESCALE_MSK;
110 tmp = (prescale + 1) * NSEC_PER_SEC * SPRD_PWM_MOD_MAX;
111 state->period = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate);
112
113 val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_DUTY);
114 duty = val & SPRD_PWM_DUTY_MSK;
115 tmp = (prescale + 1) * NSEC_PER_SEC * duty;
116 state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate);
117 state->polarity = PWM_POLARITY_NORMAL;
118
119 /* Disable PWM clocks if the PWM channel is not in enable state. */
120 if (!state->enabled)
121 clk_bulk_disable_unprepare(SPRD_PWM_CHN_CLKS_NUM, chn->clks);
122
123 return 0;
124}
125
126static int sprd_pwm_config(struct sprd_pwm_chip *spc, struct pwm_device *pwm,
127 int duty_ns, int period_ns)
128{
129 struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm];
130 u32 prescale, duty;
131 u64 tmp;
132
133 /*
134 * The hardware provides a counter that is feed by the source clock.
135 * The period length is (PRESCALE + 1) * MOD counter steps.
136 * The duty cycle length is (PRESCALE + 1) * DUTY counter steps.
137 *
138 * To keep the maths simple we're always using MOD = SPRD_PWM_MOD_MAX.
139 * The value for PRESCALE is selected such that the resulting period
140 * gets the maximal length not bigger than the requested one with the
141 * given settings (MOD = SPRD_PWM_MOD_MAX and input clock).
142 */
143 duty = duty_ns * SPRD_PWM_MOD_MAX / period_ns;
144
145 tmp = (u64)chn->clk_rate * period_ns;
146 do_div(tmp, NSEC_PER_SEC);
147 prescale = DIV_ROUND_CLOSEST_ULL(tmp, SPRD_PWM_MOD_MAX) - 1;
148 if (prescale > SPRD_PWM_PRESCALE_MSK)
149 prescale = SPRD_PWM_PRESCALE_MSK;
150
151 /*
152 * Note: Writing DUTY triggers the hardware to actually apply the
153 * values written to MOD and DUTY to the output, so must keep writing
154 * DUTY last.
155 *
156 * The hardware can ensures that current running period is completed
157 * before changing a new configuration to avoid mixed settings.
158 */
159 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_PRESCALE, prescale);
160 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_MOD, SPRD_PWM_MOD_MAX);
161 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_DUTY, duty);
162
163 return 0;
164}
165
166static int sprd_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
167 const struct pwm_state *state)
168{
169 struct sprd_pwm_chip *spc = sprd_pwm_from_chip(chip);
170 struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm];
171 struct pwm_state *cstate = &pwm->state;
172 int ret;
173
174 if (state->polarity != PWM_POLARITY_NORMAL)
175 return -EINVAL;
176
177 if (state->enabled) {
178 if (!cstate->enabled) {
179 /*
180 * The clocks to PWM channel has to be enabled first
181 * before writing to the registers.
182 */
183 ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM,
184 chn->clks);
185 if (ret) {
186 dev_err(spc->dev,
187 "failed to enable pwm%u clocks\n",
188 pwm->hwpwm);
189 return ret;
190 }
191 }
192
193 ret = sprd_pwm_config(spc, pwm, state->duty_cycle,
194 state->period);
195 if (ret)
196 return ret;
197
198 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_ENABLE, 1);
199 } else if (cstate->enabled) {
200 /*
201 * Note: After setting SPRD_PWM_ENABLE to zero, the controller
202 * will not wait for current period to be completed, instead it
203 * will stop the PWM channel immediately.
204 */
205 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_ENABLE, 0);
206
207 clk_bulk_disable_unprepare(SPRD_PWM_CHN_CLKS_NUM, chn->clks);
208 }
209
210 return 0;
211}
212
213static const struct pwm_ops sprd_pwm_ops = {
214 .apply = sprd_pwm_apply,
215 .get_state = sprd_pwm_get_state,
216};
217
218static int sprd_pwm_clk_init(struct sprd_pwm_chip *spc)
219{
220 struct clk *clk_pwm;
221 int ret, i;
222
223 for (i = 0; i < SPRD_PWM_CHN_NUM; i++) {
224 struct sprd_pwm_chn *chn = &spc->chn[i];
225 int j;
226
227 for (j = 0; j < SPRD_PWM_CHN_CLKS_NUM; ++j)
228 chn->clks[j].id =
229 sprd_pwm_clks[i * SPRD_PWM_CHN_CLKS_NUM + j];
230
231 ret = devm_clk_bulk_get(spc->dev, SPRD_PWM_CHN_CLKS_NUM,
232 chn->clks);
233 if (ret) {
234 if (ret == -ENOENT)
235 break;
236
237 return dev_err_probe(spc->dev, ret,
238 "failed to get channel clocks\n");
239 }
240
241 clk_pwm = chn->clks[SPRD_PWM_CHN_OUTPUT_CLK].clk;
242 chn->clk_rate = clk_get_rate(clk_pwm);
243 }
244
245 if (!i)
246 return dev_err_probe(spc->dev, -ENODEV, "no available PWM channels\n");
247
248 spc->num_pwms = i;
249
250 return 0;
251}
252
253static int sprd_pwm_probe(struct platform_device *pdev)
254{
255 struct sprd_pwm_chip *spc;
256 int ret;
257
258 spc = devm_kzalloc(&pdev->dev, sizeof(*spc), GFP_KERNEL);
259 if (!spc)
260 return -ENOMEM;
261
262 spc->base = devm_platform_ioremap_resource(pdev, 0);
263 if (IS_ERR(spc->base))
264 return PTR_ERR(spc->base);
265
266 spc->dev = &pdev->dev;
267
268 ret = sprd_pwm_clk_init(spc);
269 if (ret)
270 return ret;
271
272 spc->chip.dev = &pdev->dev;
273 spc->chip.ops = &sprd_pwm_ops;
274 spc->chip.npwm = spc->num_pwms;
275
276 ret = devm_pwmchip_add(&pdev->dev, &spc->chip);
277 if (ret)
278 dev_err(&pdev->dev, "failed to add PWM chip\n");
279
280 return ret;
281}
282
283static const struct of_device_id sprd_pwm_of_match[] = {
284 { .compatible = "sprd,ums512-pwm", },
285 { },
286};
287MODULE_DEVICE_TABLE(of, sprd_pwm_of_match);
288
289static struct platform_driver sprd_pwm_driver = {
290 .driver = {
291 .name = "sprd-pwm",
292 .of_match_table = sprd_pwm_of_match,
293 },
294 .probe = sprd_pwm_probe,
295};
296
297module_platform_driver(sprd_pwm_driver);
298
299MODULE_DESCRIPTION("Spreadtrum PWM Driver");
300MODULE_LICENSE("GPL v2");