1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * R-Car PWM Timer driver
4 *
5 * Copyright (C) 2015 Renesas Electronics Corporation
6 *
7 * Limitations:
8 * - The hardware cannot generate a 0% duty cycle.
9 */
10
11 #include <linux/bitfield.h>
12 #include <linux/clk.h>
13 #include <linux/err.h>
14 #include <linux/io.h>
15 #include <linux/log2.h>
16 #include <linux/math64.h>
17 #include <linux/module.h>
18 #include <linux/of.h>
19 #include <linux/platform_device.h>
20 #include <linux/pm_runtime.h>
21 #include <linux/pwm.h>
22 #include <linux/slab.h>
23
24 #define RCAR_PWM_MAX_DIVISION 24
25 #define RCAR_PWM_MAX_CYCLE 1023
26
27 #define RCAR_PWMCR 0x00
28 #define RCAR_PWMCR_CC0_MASK 0x000f0000
29 #define RCAR_PWMCR_CC0_SHIFT 16
30 #define RCAR_PWMCR_CCMD BIT(15)
31 #define RCAR_PWMCR_SYNC BIT(11)
32 #define RCAR_PWMCR_SS0 BIT(4)
33 #define RCAR_PWMCR_EN0 BIT(0)
34
35 #define RCAR_PWMCNT 0x04
36 #define RCAR_PWMCNT_CYC0_MASK 0x03ff0000
37 #define RCAR_PWMCNT_CYC0_SHIFT 16
38 #define RCAR_PWMCNT_PH0_MASK 0x000003ff
39 #define RCAR_PWMCNT_PH0_SHIFT 0
40
41 struct rcar_pwm_chip {
42 void __iomem *base;
43 struct clk *clk;
44 };
45
to_rcar_pwm_chip(struct pwm_chip * chip)46 static inline struct rcar_pwm_chip *to_rcar_pwm_chip(struct pwm_chip *chip)
47 {
48 return pwmchip_get_drvdata(chip);
49 }
50
rcar_pwm_write(struct rcar_pwm_chip * rp,u32 data,unsigned int offset)51 static void rcar_pwm_write(struct rcar_pwm_chip *rp, u32 data,
52 unsigned int offset)
53 {
54 writel(data, rp->base + offset);
55 }
56
rcar_pwm_read(struct rcar_pwm_chip * rp,unsigned int offset)57 static u32 rcar_pwm_read(struct rcar_pwm_chip *rp, unsigned int offset)
58 {
59 return readl(rp->base + offset);
60 }
61
rcar_pwm_update(struct rcar_pwm_chip * rp,u32 mask,u32 data,unsigned int offset)62 static void rcar_pwm_update(struct rcar_pwm_chip *rp, u32 mask, u32 data,
63 unsigned int offset)
64 {
65 u32 value;
66
67 value = rcar_pwm_read(rp, offset);
68 value &= ~mask;
69 value |= data & mask;
70 rcar_pwm_write(rp, value, offset);
71 }
72
rcar_pwm_get_clock_division(struct rcar_pwm_chip * rp,int period_ns)73 static int rcar_pwm_get_clock_division(struct rcar_pwm_chip *rp, int period_ns)
74 {
75 unsigned long clk_rate = clk_get_rate(rp->clk);
76 u64 div, tmp;
77
78 if (clk_rate == 0)
79 return -EINVAL;
80
81 div = (u64)NSEC_PER_SEC * RCAR_PWM_MAX_CYCLE;
82 tmp = (u64)period_ns * clk_rate + div - 1;
83 tmp = div64_u64(tmp, div);
84 div = ilog2(tmp - 1) + 1;
85
86 return (div <= RCAR_PWM_MAX_DIVISION) ? div : -ERANGE;
87 }
88
rcar_pwm_set_clock_control(struct rcar_pwm_chip * rp,unsigned int div)89 static void rcar_pwm_set_clock_control(struct rcar_pwm_chip *rp,
90 unsigned int div)
91 {
92 u32 value;
93
94 value = rcar_pwm_read(rp, RCAR_PWMCR);
95 value &= ~(RCAR_PWMCR_CCMD | RCAR_PWMCR_CC0_MASK);
96
97 if (div & 1)
98 value |= RCAR_PWMCR_CCMD;
99
100 div >>= 1;
101
102 value |= div << RCAR_PWMCR_CC0_SHIFT;
103 rcar_pwm_write(rp, value, RCAR_PWMCR);
104 }
105
rcar_pwm_set_counter(struct rcar_pwm_chip * rp,int div,u64 duty_ns,u64 period_ns)106 static int rcar_pwm_set_counter(struct rcar_pwm_chip *rp, int div, u64 duty_ns,
107 u64 period_ns)
108 {
109 unsigned long long tmp;
110 unsigned long clk_rate = clk_get_rate(rp->clk);
111 u32 cyc, ph;
112
113 /* div <= 24 == RCAR_PWM_MAX_DIVISION, so the shift doesn't overflow. */
114 tmp = mul_u64_u64_div_u64(period_ns, clk_rate, (u64)NSEC_PER_SEC << div);
115 if (tmp > FIELD_MAX(RCAR_PWMCNT_CYC0_MASK))
116 tmp = FIELD_MAX(RCAR_PWMCNT_CYC0_MASK);
117
118 cyc = FIELD_PREP(RCAR_PWMCNT_CYC0_MASK, tmp);
119
120 tmp = mul_u64_u64_div_u64(duty_ns, clk_rate, (u64)NSEC_PER_SEC << div);
121 if (tmp > FIELD_MAX(RCAR_PWMCNT_PH0_MASK))
122 tmp = FIELD_MAX(RCAR_PWMCNT_PH0_MASK);
123 ph = FIELD_PREP(RCAR_PWMCNT_PH0_MASK, tmp);
124
125 /* Avoid prohibited setting */
126 if (cyc == 0 || ph == 0)
127 return -EINVAL;
128
129 rcar_pwm_write(rp, cyc | ph, RCAR_PWMCNT);
130
131 return 0;
132 }
133
rcar_pwm_request(struct pwm_chip * chip,struct pwm_device * pwm)134 static int rcar_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
135 {
136 return pm_runtime_get_sync(pwmchip_parent(chip));
137 }
138
rcar_pwm_free(struct pwm_chip * chip,struct pwm_device * pwm)139 static void rcar_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
140 {
141 pm_runtime_put(pwmchip_parent(chip));
142 }
143
rcar_pwm_enable(struct rcar_pwm_chip * rp)144 static int rcar_pwm_enable(struct rcar_pwm_chip *rp)
145 {
146 u32 value;
147
148 /* Don't enable the PWM device if CYC0 or PH0 is 0 */
149 value = rcar_pwm_read(rp, RCAR_PWMCNT);
150 if ((value & RCAR_PWMCNT_CYC0_MASK) == 0 ||
151 (value & RCAR_PWMCNT_PH0_MASK) == 0)
152 return -EINVAL;
153
154 rcar_pwm_update(rp, RCAR_PWMCR_EN0, RCAR_PWMCR_EN0, RCAR_PWMCR);
155
156 return 0;
157 }
158
rcar_pwm_disable(struct rcar_pwm_chip * rp)159 static void rcar_pwm_disable(struct rcar_pwm_chip *rp)
160 {
161 rcar_pwm_update(rp, RCAR_PWMCR_EN0, 0, RCAR_PWMCR);
162 }
163
rcar_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)164 static int rcar_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
165 const struct pwm_state *state)
166 {
167 struct rcar_pwm_chip *rp = to_rcar_pwm_chip(chip);
168 int div, ret;
169
170 /* This HW/driver only supports normal polarity */
171 if (state->polarity != PWM_POLARITY_NORMAL)
172 return -EINVAL;
173
174 if (!state->enabled) {
175 rcar_pwm_disable(rp);
176 return 0;
177 }
178
179 div = rcar_pwm_get_clock_division(rp, state->period);
180 if (div < 0)
181 return div;
182
183 rcar_pwm_update(rp, RCAR_PWMCR_SYNC, RCAR_PWMCR_SYNC, RCAR_PWMCR);
184
185 ret = rcar_pwm_set_counter(rp, div, state->duty_cycle, state->period);
186 if (!ret)
187 rcar_pwm_set_clock_control(rp, div);
188
189 /* The SYNC should be set to 0 even if rcar_pwm_set_counter failed */
190 rcar_pwm_update(rp, RCAR_PWMCR_SYNC, 0, RCAR_PWMCR);
191
192 if (!ret)
193 ret = rcar_pwm_enable(rp);
194
195 return ret;
196 }
197
198 static const struct pwm_ops rcar_pwm_ops = {
199 .request = rcar_pwm_request,
200 .free = rcar_pwm_free,
201 .apply = rcar_pwm_apply,
202 };
203
rcar_pwm_probe(struct platform_device * pdev)204 static int rcar_pwm_probe(struct platform_device *pdev)
205 {
206 struct pwm_chip *chip;
207 struct rcar_pwm_chip *rcar_pwm;
208 int ret;
209
210 chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*rcar_pwm));
211 if (IS_ERR(chip))
212 return PTR_ERR(chip);
213 rcar_pwm = to_rcar_pwm_chip(chip);
214
215 rcar_pwm->base = devm_platform_ioremap_resource(pdev, 0);
216 if (IS_ERR(rcar_pwm->base))
217 return PTR_ERR(rcar_pwm->base);
218
219 rcar_pwm->clk = devm_clk_get(&pdev->dev, NULL);
220 if (IS_ERR(rcar_pwm->clk)) {
221 dev_err(&pdev->dev, "cannot get clock\n");
222 return PTR_ERR(rcar_pwm->clk);
223 }
224
225 chip->ops = &rcar_pwm_ops;
226
227 platform_set_drvdata(pdev, chip);
228
229 pm_runtime_enable(&pdev->dev);
230
231 ret = pwmchip_add(chip);
232 if (ret < 0) {
233 dev_err(&pdev->dev, "failed to register PWM chip: %d\n", ret);
234 pm_runtime_disable(&pdev->dev);
235 return ret;
236 }
237
238 return 0;
239 }
240
rcar_pwm_remove(struct platform_device * pdev)241 static void rcar_pwm_remove(struct platform_device *pdev)
242 {
243 struct pwm_chip *chip = platform_get_drvdata(pdev);
244
245 pwmchip_remove(chip);
246
247 pm_runtime_disable(&pdev->dev);
248 }
249
250 static const struct of_device_id rcar_pwm_of_table[] = {
251 { .compatible = "renesas,pwm-rcar", },
252 { },
253 };
254 MODULE_DEVICE_TABLE(of, rcar_pwm_of_table);
255
256 static struct platform_driver rcar_pwm_driver = {
257 .probe = rcar_pwm_probe,
258 .remove = rcar_pwm_remove,
259 .driver = {
260 .name = "pwm-rcar",
261 .of_match_table = rcar_pwm_of_table,
262 }
263 };
264 module_platform_driver(rcar_pwm_driver);
265
266 MODULE_AUTHOR("Yoshihiro Shimoda <[email protected]>");
267 MODULE_DESCRIPTION("Renesas PWM Timer Driver");
268 MODULE_LICENSE("GPL v2");
269 MODULE_ALIAS("platform:pwm-rcar");
270