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 rate = clk_get_rate(ip->clk);
89
90 value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
91
92 if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm)))
93 state->enabled = true;
94 else
95 state->enabled = false;
96
97 if (value & BIT(IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm)))
98 state->polarity = PWM_POLARITY_NORMAL;
99 else
100 state->polarity = PWM_POLARITY_INVERSED;
101
102 value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
103 prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
104 prescale &= IPROC_PWM_PRESCALE_MAX;
105
106 multi = NSEC_PER_SEC * (prescale + 1);
107
108 value = readl(ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
109 tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
110 state->period = div64_u64(tmp, rate);
111
112 value = readl(ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
113 tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
114 state->duty_cycle = div64_u64(tmp, rate);
115 }
116
iproc_pwmc_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)117 static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
118 const struct pwm_state *state)
119 {
120 unsigned long prescale = IPROC_PWM_PRESCALE_MIN;
121 struct iproc_pwmc *ip = to_iproc_pwmc(chip);
122 u32 value, period, duty;
123 u64 rate;
124
125 rate = clk_get_rate(ip->clk);
126
127 /*
128 * Find period count, duty count and prescale to suit duty_cycle and
129 * period. This is done according to formulas described below:
130 *
131 * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE
132 * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
133 *
134 * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
135 * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
136 */
137 while (1) {
138 u64 value, div;
139
140 div = NSEC_PER_SEC * (prescale + 1);
141 value = rate * state->period;
142 period = div64_u64(value, div);
143 value = rate * state->duty_cycle;
144 duty = div64_u64(value, div);
145
146 if (period < IPROC_PWM_PERIOD_MIN ||
147 duty < IPROC_PWM_DUTY_CYCLE_MIN)
148 return -EINVAL;
149
150 if (period <= IPROC_PWM_PERIOD_MAX &&
151 duty <= IPROC_PWM_DUTY_CYCLE_MAX)
152 break;
153
154 /* Otherwise, increase prescale and recalculate counts */
155 if (++prescale > IPROC_PWM_PRESCALE_MAX)
156 return -EINVAL;
157 }
158
159 iproc_pwmc_disable(ip, pwm->hwpwm);
160
161 /* Set prescale */
162 value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
163 value &= ~IPROC_PWM_PRESCALE_MASK(pwm->hwpwm);
164 value |= prescale << IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
165 writel(value, ip->base + IPROC_PWM_PRESCALE_OFFSET);
166
167 /* set period and duty cycle */
168 writel(period, ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
169 writel(duty, ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
170
171 /* set polarity */
172 value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
173
174 if (state->polarity == PWM_POLARITY_NORMAL)
175 value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm);
176 else
177 value &= ~(1 << IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm));
178
179 writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
180
181 if (state->enabled)
182 iproc_pwmc_enable(ip, pwm->hwpwm);
183
184 return 0;
185 }
186
187 static const struct pwm_ops iproc_pwm_ops = {
188 .apply = iproc_pwmc_apply,
189 .get_state = iproc_pwmc_get_state,
190 .owner = THIS_MODULE,
191 };
192
iproc_pwmc_probe(struct platform_device * pdev)193 static int iproc_pwmc_probe(struct platform_device *pdev)
194 {
195 struct iproc_pwmc *ip;
196 struct resource *res;
197 unsigned int i;
198 u32 value;
199 int ret;
200
201 ip = devm_kzalloc(&pdev->dev, sizeof(*ip), GFP_KERNEL);
202 if (!ip)
203 return -ENOMEM;
204
205 platform_set_drvdata(pdev, ip);
206
207 ip->chip.dev = &pdev->dev;
208 ip->chip.ops = &iproc_pwm_ops;
209 ip->chip.base = -1;
210 ip->chip.npwm = 4;
211 ip->chip.of_xlate = of_pwm_xlate_with_flags;
212 ip->chip.of_pwm_n_cells = 3;
213
214 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
215 ip->base = devm_ioremap_resource(&pdev->dev, res);
216 if (IS_ERR(ip->base))
217 return PTR_ERR(ip->base);
218
219 ip->clk = devm_clk_get(&pdev->dev, NULL);
220 if (IS_ERR(ip->clk)) {
221 dev_err(&pdev->dev, "failed to get clock: %ld\n",
222 PTR_ERR(ip->clk));
223 return PTR_ERR(ip->clk);
224 }
225
226 ret = clk_prepare_enable(ip->clk);
227 if (ret < 0) {
228 dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
229 return ret;
230 }
231
232 /* Set full drive and normal polarity for all channels */
233 value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
234
235 for (i = 0; i < ip->chip.npwm; i++) {
236 value &= ~(1 << IPROC_PWM_CTRL_TYPE_SHIFT(i));
237 value |= 1 << IPROC_PWM_CTRL_POLARITY_SHIFT(i);
238 }
239
240 writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);
241
242 ret = pwmchip_add(&ip->chip);
243 if (ret < 0) {
244 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
245 clk_disable_unprepare(ip->clk);
246 }
247
248 return ret;
249 }
250
iproc_pwmc_remove(struct platform_device * pdev)251 static int iproc_pwmc_remove(struct platform_device *pdev)
252 {
253 struct iproc_pwmc *ip = platform_get_drvdata(pdev);
254
255 clk_disable_unprepare(ip->clk);
256
257 return pwmchip_remove(&ip->chip);
258 }
259
260 static const struct of_device_id bcm_iproc_pwmc_dt[] = {
261 { .compatible = "brcm,iproc-pwm" },
262 { },
263 };
264 MODULE_DEVICE_TABLE(of, bcm_iproc_pwmc_dt);
265
266 static struct platform_driver iproc_pwmc_driver = {
267 .driver = {
268 .name = "bcm-iproc-pwm",
269 .of_match_table = bcm_iproc_pwmc_dt,
270 },
271 .probe = iproc_pwmc_probe,
272 .remove = iproc_pwmc_remove,
273 };
274 module_platform_driver(iproc_pwmc_driver);
275
276 MODULE_AUTHOR("Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>");
277 MODULE_DESCRIPTION("Broadcom iProc PWM driver");
278 MODULE_LICENSE("GPL v2");
279