1 /*
2 * Copyright (C) 2016 Broadcom
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation version 2.
7 *
8 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
9 * kind, whether express or implied; without even the implied warranty
10 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 */
13
14 #include <linux/clk.h>
15 #include <linux/delay.h>
16 #include <linux/err.h>
17 #include <linux/io.h>
18 #include <linux/math64.h>
19 #include <linux/module.h>
20 #include <linux/of.h>
21 #include <linux/platform_device.h>
22 #include <linux/pwm.h>
23
24 #define IPROC_PWM_CTRL_OFFSET 0x00
25 #define IPROC_PWM_CTRL_TYPE_SHIFT(ch) (15 + (ch))
26 #define IPROC_PWM_CTRL_POLARITY_SHIFT(ch) (8 + (ch))
27 #define IPROC_PWM_CTRL_EN_SHIFT(ch) (ch)
28
29 #define IPROC_PWM_PERIOD_OFFSET(ch) (0x04 + ((ch) << 3))
30 #define IPROC_PWM_PERIOD_MIN 0x02
31 #define IPROC_PWM_PERIOD_MAX 0xffff
32
33 #define IPROC_PWM_DUTY_CYCLE_OFFSET(ch) (0x08 + ((ch) << 3))
34 #define IPROC_PWM_DUTY_CYCLE_MIN 0x00
35 #define IPROC_PWM_DUTY_CYCLE_MAX 0xffff
36
37 #define IPROC_PWM_PRESCALE_OFFSET 0x24
38 #define IPROC_PWM_PRESCALE_BITS 0x06
39 #define IPROC_PWM_PRESCALE_SHIFT(ch) ((3 - (ch)) * \
40 IPROC_PWM_PRESCALE_BITS)
41 #define IPROC_PWM_PRESCALE_MASK(ch) (IPROC_PWM_PRESCALE_MAX << \
42 IPROC_PWM_PRESCALE_SHIFT(ch))
43 #define IPROC_PWM_PRESCALE_MIN 0x00
44 #define IPROC_PWM_PRESCALE_MAX 0x3f
45
46 struct iproc_pwmc {
47 struct pwm_chip chip;
48 void __iomem *base;
49 struct clk *clk;
50 };
51
to_iproc_pwmc(struct pwm_chip * chip)52 static inline struct iproc_pwmc *to_iproc_pwmc(struct pwm_chip *chip)
53 {
54 return container_of(chip, struct iproc_pwmc, chip);
55 }
56
iproc_pwmc_enable(struct iproc_pwmc * ip,unsigned int channel)57 static void iproc_pwmc_enable(struct iproc_pwmc *ip, unsigned int channel)
58 {
59 u32 value;
60
61 value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
62 value |= 1 << IPROC_PWM_CTRL_EN_SHIFT(channel);
63 writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
64
65 /* must be a 400 ns delay between clearing and setting enable bit */
66 ndelay(400);
67 }
68
iproc_pwmc_disable(struct iproc_pwmc * ip,unsigned int channel)69 static void iproc_pwmc_disable(struct iproc_pwmc *ip, unsigned int channel)
70 {
71 u32 value;
72
73 value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
74 value &= ~(1 << IPROC_PWM_CTRL_EN_SHIFT(channel));
75 writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
76
77 /* must be a 400 ns delay between clearing and setting enable bit */
78 ndelay(400);
79 }
80
iproc_pwmc_get_state(struct pwm_chip * chip,struct pwm_device * pwm,struct pwm_state * state)81 static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
82 struct pwm_state *state)
83 {
84 struct iproc_pwmc *ip = to_iproc_pwmc(chip);
85 u64 tmp, multi, rate;
86 u32 value, prescale;
87
88 value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
89
90 if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm)))
91 state->enabled = true;
92 else
93 state->enabled = false;
94
95 if (value & BIT(IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm)))
96 state->polarity = PWM_POLARITY_NORMAL;
97 else
98 state->polarity = PWM_POLARITY_INVERSED;
99
100 rate = clk_get_rate(ip->clk);
101 if (rate == 0) {
102 state->period = 0;
103 state->duty_cycle = 0;
104 return;
105 }
106
107 value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
108 prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
109 prescale &= IPROC_PWM_PRESCALE_MAX;
110
111 multi = NSEC_PER_SEC * (prescale + 1);
112
113 value = readl(ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
114 tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
115 state->period = div64_u64(tmp, rate);
116
117 value = readl(ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
118 tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
119 state->duty_cycle = div64_u64(tmp, rate);
120 }
121
iproc_pwmc_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)122 static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
123 const struct pwm_state *state)
124 {
125 unsigned long prescale = IPROC_PWM_PRESCALE_MIN;
126 struct iproc_pwmc *ip = to_iproc_pwmc(chip);
127 u32 value, period, duty;
128 u64 rate;
129
130 rate = clk_get_rate(ip->clk);
131
132 /*
133 * Find period count, duty count and prescale to suit duty_cycle and
134 * period. This is done according to formulas described below:
135 *
136 * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE
137 * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
138 *
139 * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
140 * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
141 */
142 while (1) {
143 u64 value, div;
144
145 div = NSEC_PER_SEC * (prescale + 1);
146 value = rate * state->period;
147 period = div64_u64(value, div);
148 value = rate * state->duty_cycle;
149 duty = div64_u64(value, div);
150
151 if (period < IPROC_PWM_PERIOD_MIN)
152 return -EINVAL;
153
154 if (period <= IPROC_PWM_PERIOD_MAX &&
155 duty <= IPROC_PWM_DUTY_CYCLE_MAX)
156 break;
157
158 /* Otherwise, increase prescale and recalculate counts */
159 if (++prescale > IPROC_PWM_PRESCALE_MAX)
160 return -EINVAL;
161 }
162
163 iproc_pwmc_disable(ip, pwm->hwpwm);
164
165 /* Set prescale */
166 value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
167 value &= ~IPROC_PWM_PRESCALE_MASK(pwm->hwpwm);
168 value |= prescale << IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
169 writel(value, ip->base + IPROC_PWM_PRESCALE_OFFSET);
170
171 /* set period and duty cycle */
172 writel(period, ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
173 writel(duty, ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
174
175 /* set polarity */
176 value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
177
178 if (state->polarity == PWM_POLARITY_NORMAL)
179 value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm);
180 else
181 value &= ~(1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm));
182
183 writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
184
185 if (state->enabled)
186 iproc_pwmc_enable(ip, pwm->hwpwm);
187
188 return 0;
189 }
190
191 static const struct pwm_ops iproc_pwm_ops = {
192 .apply = iproc_pwmc_apply,
193 .get_state = iproc_pwmc_get_state,
194 .owner = THIS_MODULE,
195 };
196
iproc_pwmc_probe(struct platform_device * pdev)197 static int iproc_pwmc_probe(struct platform_device *pdev)
198 {
199 struct iproc_pwmc *ip;
200 unsigned int i;
201 u32 value;
202 int ret;
203
204 ip = devm_kzalloc(&pdev->dev, sizeof(*ip), GFP_KERNEL);
205 if (!ip)
206 return -ENOMEM;
207
208 platform_set_drvdata(pdev, ip);
209
210 ip->chip.dev = &pdev->dev;
211 ip->chip.ops = &iproc_pwm_ops;
212 ip->chip.npwm = 4;
213
214 ip->base = devm_platform_ioremap_resource(pdev, 0);
215 if (IS_ERR(ip->base))
216 return PTR_ERR(ip->base);
217
218 ip->clk = devm_clk_get(&pdev->dev, NULL);
219 if (IS_ERR(ip->clk)) {
220 dev_err(&pdev->dev, "failed to get clock: %ld\n",
221 PTR_ERR(ip->clk));
222 return PTR_ERR(ip->clk);
223 }
224
225 ret = clk_prepare_enable(ip->clk);
226 if (ret < 0) {
227 dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
228 return ret;
229 }
230
231 /* Set full drive and normal polarity for all channels */
232 value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
233
234 for (i = 0; i < ip->chip.npwm; i++) {
235 value &= ~(1 << IPROC_PWM_CTRL_TYPE_SHIFT(i));
236 value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(i);
237 }
238
239 writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
240
241 ret = pwmchip_add(&ip->chip);
242 if (ret < 0) {
243 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
244 clk_disable_unprepare(ip->clk);
245 }
246
247 return ret;
248 }
249
iproc_pwmc_remove(struct platform_device * pdev)250 static int iproc_pwmc_remove(struct platform_device *pdev)
251 {
252 struct iproc_pwmc *ip = platform_get_drvdata(pdev);
253
254 pwmchip_remove(&ip->chip);
255
256 clk_disable_unprepare(ip->clk);
257
258 return 0;
259 }
260
261 static const struct of_device_id bcm_iproc_pwmc_dt[] = {
262 { .compatible = "brcm,iproc-pwm" },
263 { },
264 };
265 MODULE_DEVICE_TABLE(of, bcm_iproc_pwmc_dt);
266
267 static struct platform_driver iproc_pwmc_driver = {
268 .driver = {
269 .name = "bcm-iproc-pwm",
270 .of_match_table = bcm_iproc_pwmc_dt,
271 },
272 .probe = iproc_pwmc_probe,
273 .remove = iproc_pwmc_remove,
274 };
275 module_platform_driver(iproc_pwmc_driver);
276
277 MODULE_AUTHOR("Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>");
278 MODULE_DESCRIPTION("Broadcom iProc PWM driver");
279 MODULE_LICENSE("GPL v2");
280