1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Intel Low Power Subsystem PWM controller driver
4 *
5 * Copyright (C) 2014, Intel Corporation
6 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
7 * Author: Chew Kean Ho <kean.ho.chew@intel.com>
8 * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
9 * Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
10 * Author: Alan Cox <alan@linux.intel.com>
11 */
12
13#define DEFAULT_SYMBOL_NAMESPACE "PWM_LPSS"
14
15#include <linux/bits.h>
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/pwm.h>
23#include <linux/time.h>
24
25#include "pwm-lpss.h"
26
27#define PWM 0x00000000
28#define PWM_ENABLE BIT(31)
29#define PWM_SW_UPDATE BIT(30)
30#define PWM_BASE_UNIT_SHIFT 8
31#define PWM_ON_TIME_DIV_MASK GENMASK(7, 0)
32
33/* Size of each PWM register space if multiple */
34#define PWM_SIZE 0x400
35
36/* BayTrail */
37const struct pwm_lpss_boardinfo pwm_lpss_byt_info = {
38 .clk_rate = 25000000,
39 .npwm = 1,
40 .base_unit_bits = 16,
41};
42EXPORT_SYMBOL_GPL(pwm_lpss_byt_info);
43
44/* Braswell */
45const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
46 .clk_rate = 19200000,
47 .npwm = 1,
48 .base_unit_bits = 16,
49 .other_devices_aml_touches_pwm_regs = true,
50};
51EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info);
52
53/* Broxton */
54const struct pwm_lpss_boardinfo pwm_lpss_bxt_info = {
55 .clk_rate = 19200000,
56 .npwm = 4,
57 .base_unit_bits = 22,
58 .bypass = true,
59};
60EXPORT_SYMBOL_GPL(pwm_lpss_bxt_info);
61
62/* Tangier */
63const struct pwm_lpss_boardinfo pwm_lpss_tng_info = {
64 .clk_rate = 19200000,
65 .npwm = 4,
66 .base_unit_bits = 22,
67};
68EXPORT_SYMBOL_GPL(pwm_lpss_tng_info);
69
70static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
71{
72 return pwmchip_get_drvdata(chip);
73}
74
75static inline u32 pwm_lpss_read(const struct pwm_device *pwm)
76{
77 struct pwm_lpss_chip *lpwm = to_lpwm(chip: pwm->chip);
78
79 return readl(addr: lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
80}
81
82static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value)
83{
84 struct pwm_lpss_chip *lpwm = to_lpwm(chip: pwm->chip);
85
86 writel(val: value, addr: lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM);
87}
88
89static int pwm_lpss_wait_for_update(struct pwm_device *pwm)
90{
91 struct pwm_lpss_chip *lpwm = to_lpwm(chip: pwm->chip);
92 const void __iomem *addr = lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM;
93 const unsigned int ms = 500 * USEC_PER_MSEC;
94 u32 val;
95 int err;
96
97 /*
98 * PWM Configuration register has SW_UPDATE bit that is set when a new
99 * configuration is written to the register. The bit is automatically
100 * cleared at the start of the next output cycle by the IP block.
101 *
102 * If one writes a new configuration to the register while it still has
103 * the bit enabled, PWM may freeze. That is, while one can still write
104 * to the register, it won't have an effect. Thus, we try to sleep long
105 * enough that the bit gets cleared and make sure the bit is not
106 * enabled while we update the configuration.
107 */
108 err = readl_poll_timeout(addr, val, !(val & PWM_SW_UPDATE), 40, ms);
109 if (err)
110 dev_err(pwmchip_parent(pwm->chip), "PWM_SW_UPDATE was not cleared\n");
111
112 return err;
113}
114
115static inline int pwm_lpss_is_updating(struct pwm_device *pwm)
116{
117 if (pwm_lpss_read(pwm) & PWM_SW_UPDATE) {
118 dev_err(pwmchip_parent(pwm->chip), "PWM_SW_UPDATE is still set, skipping update\n");
119 return -EBUSY;
120 }
121
122 return 0;
123}
124
125static void pwm_lpss_prepare(struct pwm_lpss_chip *lpwm, struct pwm_device *pwm,
126 int duty_ns, int period_ns)
127{
128 unsigned long long on_time_div;
129 unsigned long c = lpwm->info->clk_rate, base_unit_range;
130 unsigned long long base_unit, freq = NSEC_PER_SEC;
131 u32 ctrl;
132
133 do_div(freq, period_ns);
134
135 /*
136 * The equation is:
137 * base_unit = round(base_unit_range * freq / c)
138 */
139 base_unit_range = BIT(lpwm->info->base_unit_bits);
140 freq *= base_unit_range;
141
142 base_unit = DIV_ROUND_CLOSEST_ULL(freq, c);
143 /* base_unit must not be 0 and we also want to avoid overflowing it */
144 base_unit = clamp_val(base_unit, 1, base_unit_range - 1);
145
146 on_time_div = 255ULL * duty_ns;
147 do_div(on_time_div, period_ns);
148 on_time_div = 255ULL - on_time_div;
149
150 ctrl = pwm_lpss_read(pwm);
151 ctrl &= ~PWM_ON_TIME_DIV_MASK;
152 ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT);
153 ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT;
154 ctrl |= on_time_div;
155
156 pwm_lpss_write(pwm, value: ctrl);
157 pwm_lpss_write(pwm, value: ctrl | PWM_SW_UPDATE);
158}
159
160static inline void pwm_lpss_cond_enable(struct pwm_device *pwm, bool cond)
161{
162 if (cond)
163 pwm_lpss_write(pwm, value: pwm_lpss_read(pwm) | PWM_ENABLE);
164}
165
166static int pwm_lpss_prepare_enable(struct pwm_lpss_chip *lpwm,
167 struct pwm_device *pwm,
168 const struct pwm_state *state)
169{
170 int ret;
171
172 ret = pwm_lpss_is_updating(pwm);
173 if (ret)
174 return ret;
175
176 pwm_lpss_prepare(lpwm, pwm, duty_ns: state->duty_cycle, period_ns: state->period);
177 pwm_lpss_cond_enable(pwm, cond: lpwm->info->bypass == false);
178 ret = pwm_lpss_wait_for_update(pwm);
179 if (ret)
180 return ret;
181
182 pwm_lpss_cond_enable(pwm, cond: lpwm->info->bypass == true);
183 return 0;
184}
185
186static int pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm,
187 const struct pwm_state *state)
188{
189 struct pwm_lpss_chip *lpwm = to_lpwm(chip);
190 int ret = 0;
191
192 if (state->enabled) {
193 if (!pwm_is_enabled(pwm)) {
194 pm_runtime_get_sync(dev: pwmchip_parent(chip));
195 ret = pwm_lpss_prepare_enable(lpwm, pwm, state);
196 if (ret)
197 pm_runtime_put(dev: pwmchip_parent(chip));
198 } else {
199 ret = pwm_lpss_prepare_enable(lpwm, pwm, state);
200 }
201 } else if (pwm_is_enabled(pwm)) {
202 pwm_lpss_write(pwm, value: pwm_lpss_read(pwm) & ~PWM_ENABLE);
203 pm_runtime_put(dev: pwmchip_parent(chip));
204 }
205
206 return ret;
207}
208
209static int pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
210 struct pwm_state *state)
211{
212 struct pwm_lpss_chip *lpwm = to_lpwm(chip);
213 unsigned long base_unit_range;
214 unsigned long long base_unit, freq, on_time_div;
215 u32 ctrl;
216
217 pm_runtime_get_sync(dev: pwmchip_parent(chip));
218
219 base_unit_range = BIT(lpwm->info->base_unit_bits);
220
221 ctrl = pwm_lpss_read(pwm);
222 on_time_div = 255 - (ctrl & PWM_ON_TIME_DIV_MASK);
223 base_unit = (ctrl >> PWM_BASE_UNIT_SHIFT) & (base_unit_range - 1);
224
225 freq = base_unit * lpwm->info->clk_rate;
226 do_div(freq, base_unit_range);
227 if (freq == 0)
228 state->period = NSEC_PER_SEC;
229 else
230 state->period = NSEC_PER_SEC / (unsigned long)freq;
231
232 on_time_div *= state->period;
233 do_div(on_time_div, 255);
234 state->duty_cycle = on_time_div;
235
236 state->polarity = PWM_POLARITY_NORMAL;
237 state->enabled = !!(ctrl & PWM_ENABLE);
238
239 pm_runtime_put(dev: pwmchip_parent(chip));
240
241 return 0;
242}
243
244static const struct pwm_ops pwm_lpss_ops = {
245 .apply = pwm_lpss_apply,
246 .get_state = pwm_lpss_get_state,
247};
248
249struct pwm_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
250 const struct pwm_lpss_boardinfo *info)
251{
252 struct pwm_lpss_chip *lpwm;
253 struct pwm_chip *chip;
254 unsigned long c;
255 int i, ret;
256 u32 ctrl;
257
258 if (WARN_ON(info->npwm > LPSS_MAX_PWMS))
259 return ERR_PTR(error: -ENODEV);
260
261 chip = devm_pwmchip_alloc(parent: dev, npwm: info->npwm, sizeof_priv: sizeof(*lpwm));
262 if (IS_ERR(ptr: chip))
263 return chip;
264 lpwm = to_lpwm(chip);
265
266 lpwm->regs = base;
267 lpwm->info = info;
268
269 c = lpwm->info->clk_rate;
270 if (!c)
271 return ERR_PTR(error: -EINVAL);
272
273 chip->ops = &pwm_lpss_ops;
274
275 ret = devm_pwmchip_add(dev, chip);
276 if (ret) {
277 dev_err(dev, "failed to add PWM chip: %d\n", ret);
278 return ERR_PTR(error: ret);
279 }
280
281 for (i = 0; i < lpwm->info->npwm; i++) {
282 ctrl = pwm_lpss_read(pwm: &chip->pwms[i]);
283 if (ctrl & PWM_ENABLE)
284 pm_runtime_get(dev);
285 }
286
287 return chip;
288}
289EXPORT_SYMBOL_GPL(devm_pwm_lpss_probe);
290
291MODULE_DESCRIPTION("PWM driver for Intel LPSS");
292MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
293MODULE_LICENSE("GPL v2");
294

source code of linux/drivers/pwm/pwm-lpss.c