1 /*
2 * Intel Low Power Subsystem PWM controller driver
3 *
4 * Copyright (C) 2014, Intel Corporation
5 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
6 * Author: Chew Kean Ho <kean.ho.chew@intel.com>
7 * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
8 * Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
9 * Author: Alan Cox <alan@linux.intel.com>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 */
15
16 #include <linux/delay.h>
17 #include <linux/io.h>
18 #include <linux/iopoll.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/pm_runtime.h>
22 #include <linux/time.h>
23
24 #include "pwm-lpss.h"
25
26 #define PWM 0x00000000
27 #define PWM_ENABLE BIT(31)
28 #define PWM_SW_UPDATE BIT(30)
29 #define PWM_BASE_UNIT_SHIFT 8
30 #define PWM_ON_TIME_DIV_MASK 0x000000ff
31
32 /* Size of each PWM register space if multiple */
33 #define PWM_SIZE 0x400
34
35 #define MAX_PWMS 4
36
37 struct pwm_lpss_chip {
38 struct pwm_chip chip;
39 void __iomem *regs;
40 const struct pwm_lpss_boardinfo *info;
41 u32 saved_ctrl[MAX_PWMS];
42 };
43
to_lpwm(struct pwm_chip * chip)44 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
45 {
46 return container_of(chip, struct pwm_lpss_chip, chip);
47 }
48
pwm_lpss_read(const struct pwm_device * pwm)49 static inline u32 pwm_lpss_read(const struct pwm_device *pwm)
50 {
51 struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
52
53 return readl(lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
54 }
55
pwm_lpss_write(const struct pwm_device * pwm,u32 value)56 static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value)
57 {
58 struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
59
60 writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
61 }
62
pwm_lpss_wait_for_update(struct pwm_device * pwm)63 static int pwm_lpss_wait_for_update(struct pwm_device *pwm)
64 {
65 struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip);
66 const void __iomem *addr = lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM;
67 const unsigned int ms = 500 * USEC_PER_MSEC;
68 u32 val;
69 int err;
70
71 /*
72 * PWM Configuration register has SW_UPDATE bit that is set when a new
73 * configuration is written to the register. The bit is automatically
74 * cleared at the start of the next output cycle by the IP block.
75 *
76 * If one writes a new configuration to the register while it still has
77 * the bit enabled, PWM may freeze. That is, while one can still write
78 * to the register, it won't have an effect. Thus, we try to sleep long
79 * enough that the bit gets cleared and make sure the bit is not
80 * enabled while we update the configuration.
81 */
82 err = readl_poll_timeout(addr, val, !(val & PWM_SW_UPDATE), 40, ms);
83 if (err)
84 dev_err(pwm->chip->dev, "PWM_SW_UPDATE was not cleared\n");
85
86 return err;
87 }
88
pwm_lpss_is_updating(struct pwm_device * pwm)89 static inline int pwm_lpss_is_updating(struct pwm_device *pwm)
90 {
91 return (pwm_lpss_read(pwm) & PWM_SW_UPDATE) ? -EBUSY : 0;
92 }
93
pwm_lpss_prepare(struct pwm_lpss_chip * lpwm,struct pwm_device * pwm,int duty_ns,int period_ns)94 static void pwm_lpss_prepare(struct pwm_lpss_chip *lpwm, struct pwm_device *pwm,
95 int duty_ns, int period_ns)
96 {
97 unsigned long long on_time_div;
98 unsigned long c = lpwm->info->clk_rate, base_unit_range;
99 unsigned long long base_unit, freq = NSEC_PER_SEC;
100 u32 orig_ctrl, ctrl;
101
102 do_div(freq, period_ns);
103
104 /*
105 * The equation is:
106 * base_unit = round(base_unit_range * freq / c)
107 */
108 base_unit_range = BIT(lpwm->info->base_unit_bits);
109 freq *= base_unit_range;
110
111 base_unit = DIV_ROUND_CLOSEST_ULL(freq, c);
112 /* base_unit must not be 0 and we also want to avoid overflowing it */
113 base_unit = clamp_val(base_unit, 1, base_unit_range - 1);
114
115 on_time_div = 255ULL * duty_ns;
116 do_div(on_time_div, period_ns);
117 on_time_div = 255ULL - on_time_div;
118
119 orig_ctrl = ctrl = pwm_lpss_read(pwm);
120 ctrl &= ~PWM_ON_TIME_DIV_MASK;
121 ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT);
122 ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT;
123 ctrl |= on_time_div;
124
125 if (orig_ctrl != ctrl) {
126 pwm_lpss_write(pwm, ctrl);
127 pwm_lpss_write(pwm, ctrl | PWM_SW_UPDATE);
128 }
129 }
130
pwm_lpss_cond_enable(struct pwm_device * pwm,bool cond)131 static inline void pwm_lpss_cond_enable(struct pwm_device *pwm, bool cond)
132 {
133 if (cond)
134 pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE);
135 }
136
pwm_lpss_apply(struct pwm_chip * chip,struct pwm_device * pwm,struct pwm_state * state)137 static int pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm,
138 struct pwm_state *state)
139 {
140 struct pwm_lpss_chip *lpwm = to_lpwm(chip);
141 int ret;
142
143 if (state->enabled) {
144 if (!pwm_is_enabled(pwm)) {
145 pm_runtime_get_sync(chip->dev);
146 ret = pwm_lpss_is_updating(pwm);
147 if (ret) {
148 pm_runtime_put(chip->dev);
149 return ret;
150 }
151 pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period);
152 pwm_lpss_cond_enable(pwm, lpwm->info->bypass == false);
153 ret = pwm_lpss_wait_for_update(pwm);
154 if (ret) {
155 pm_runtime_put(chip->dev);
156 return ret;
157 }
158 pwm_lpss_cond_enable(pwm, lpwm->info->bypass == true);
159 } else {
160 ret = pwm_lpss_is_updating(pwm);
161 if (ret)
162 return ret;
163 pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period);
164 return pwm_lpss_wait_for_update(pwm);
165 }
166 } else if (pwm_is_enabled(pwm)) {
167 pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE);
168 pm_runtime_put(chip->dev);
169 }
170
171 return 0;
172 }
173
174 static const struct pwm_ops pwm_lpss_ops = {
175 .apply = pwm_lpss_apply,
176 .owner = THIS_MODULE,
177 };
178
pwm_lpss_probe(struct device * dev,struct resource * r,const struct pwm_lpss_boardinfo * info)179 struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
180 const struct pwm_lpss_boardinfo *info)
181 {
182 struct pwm_lpss_chip *lpwm;
183 unsigned long c;
184 int ret;
185
186 if (WARN_ON(info->npwm > MAX_PWMS))
187 return ERR_PTR(-ENODEV);
188
189 lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
190 if (!lpwm)
191 return ERR_PTR(-ENOMEM);
192
193 lpwm->regs = devm_ioremap_resource(dev, r);
194 if (IS_ERR(lpwm->regs))
195 return ERR_CAST(lpwm->regs);
196
197 lpwm->info = info;
198
199 c = lpwm->info->clk_rate;
200 if (!c)
201 return ERR_PTR(-EINVAL);
202
203 lpwm->chip.dev = dev;
204 lpwm->chip.ops = &pwm_lpss_ops;
205 lpwm->chip.base = -1;
206 lpwm->chip.npwm = info->npwm;
207
208 ret = pwmchip_add(&lpwm->chip);
209 if (ret) {
210 dev_err(dev, "failed to add PWM chip: %d\n", ret);
211 return ERR_PTR(ret);
212 }
213
214 return lpwm;
215 }
216 EXPORT_SYMBOL_GPL(pwm_lpss_probe);
217
pwm_lpss_remove(struct pwm_lpss_chip * lpwm)218 int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
219 {
220 int i;
221
222 for (i = 0; i < lpwm->info->npwm; i++) {
223 if (pwm_is_enabled(&lpwm->chip.pwms[i]))
224 pm_runtime_put(lpwm->chip.dev);
225 }
226 return pwmchip_remove(&lpwm->chip);
227 }
228 EXPORT_SYMBOL_GPL(pwm_lpss_remove);
229
pwm_lpss_suspend(struct device * dev)230 int pwm_lpss_suspend(struct device *dev)
231 {
232 struct pwm_lpss_chip *lpwm = dev_get_drvdata(dev);
233 int i;
234
235 for (i = 0; i < lpwm->info->npwm; i++)
236 lpwm->saved_ctrl[i] = readl(lpwm->regs + i * PWM_SIZE + PWM);
237
238 return 0;
239 }
240 EXPORT_SYMBOL_GPL(pwm_lpss_suspend);
241
pwm_lpss_resume(struct device * dev)242 int pwm_lpss_resume(struct device *dev)
243 {
244 struct pwm_lpss_chip *lpwm = dev_get_drvdata(dev);
245 int i;
246
247 for (i = 0; i < lpwm->info->npwm; i++)
248 writel(lpwm->saved_ctrl[i], lpwm->regs + i * PWM_SIZE + PWM);
249
250 return 0;
251 }
252 EXPORT_SYMBOL_GPL(pwm_lpss_resume);
253
254 MODULE_DESCRIPTION("PWM driver for Intel LPSS");
255 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
256 MODULE_LICENSE("GPL v2");
257