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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * DesignWare PWM Controller driver core
4 *
5 * Copyright (C) 2018-2020 Intel Corporation
6 *
7 * Author: Felipe Balbi (Intel)
8 * Author: Jarkko Nikula <[email protected]>
9 * Author: Raymond Tan <[email protected]>
10 */
11
12#define DEFAULT_SYMBOL_NAMESPACE "dwc_pwm"
13
14#include <linux/bitops.h>
15#include <linux/export.h>
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/pci.h>
19#include <linux/pm_runtime.h>
20#include <linux/pwm.h>
21
22#include "pwm-dwc.h"
23
24static void __dwc_pwm_set_enable(struct dwc_pwm *dwc, int pwm, int enabled)
25{
26 u32 reg;
27
28 reg = dwc_pwm_readl(dwc, DWC_TIM_CTRL(pwm));
29
30 if (enabled)
31 reg |= DWC_TIM_CTRL_EN;
32 else
33 reg &= ~DWC_TIM_CTRL_EN;
34
35 dwc_pwm_writel(dwc, reg, DWC_TIM_CTRL(pwm));
36}
37
38static int __dwc_pwm_configure_timer(struct dwc_pwm *dwc,
39 struct pwm_device *pwm,
40 const struct pwm_state *state)
41{
42 u64 tmp;
43 u32 ctrl;
44 u32 high;
45 u32 low;
46
47 /*
48 * Calculate width of low and high period in terms of input clock
49 * periods and check are the result within HW limits between 1 and
50 * 2^32 periods.
51 */
52 tmp = DIV_ROUND_CLOSEST_ULL(state->duty_cycle, dwc->clk_ns);
53 if (tmp < 1 || tmp > (1ULL << 32))
54 return -ERANGE;
55 low = tmp - 1;
56
57 tmp = DIV_ROUND_CLOSEST_ULL(state->period - state->duty_cycle,
58 dwc->clk_ns);
59 if (tmp < 1 || tmp > (1ULL << 32))
60 return -ERANGE;
61 high = tmp - 1;
62
63 /*
64 * Specification says timer usage flow is to disable timer, then
65 * program it followed by enable. It also says Load Count is loaded
66 * into timer after it is enabled - either after a disable or
67 * a reset. Based on measurements it happens also without disable
68 * whenever Load Count is updated. But follow the specification.
69 */
70 __dwc_pwm_set_enable(dwc, pwm->hwpwm, false);
71
72 /*
73 * Write Load Count and Load Count 2 registers. Former defines the
74 * width of low period and latter the width of high period in terms
75 * multiple of input clock periods:
76 * Width = ((Count + 1) * input clock period).
77 */
78 dwc_pwm_writel(dwc, low, DWC_TIM_LD_CNT(pwm->hwpwm));
79 dwc_pwm_writel(dwc, high, DWC_TIM_LD_CNT2(pwm->hwpwm));
80
81 /*
82 * Set user-defined mode, timer reloads from Load Count registers
83 * when it counts down to 0.
84 * Set PWM mode, it makes output to toggle and width of low and high
85 * periods are set by Load Count registers.
86 */
87 ctrl = DWC_TIM_CTRL_MODE_USER | DWC_TIM_CTRL_PWM;
88 dwc_pwm_writel(dwc, ctrl, DWC_TIM_CTRL(pwm->hwpwm));
89
90 /*
91 * Enable timer. Output starts from low period.
92 */
93 __dwc_pwm_set_enable(dwc, pwm->hwpwm, state->enabled);
94
95 return 0;
96}
97
98static int dwc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
99 const struct pwm_state *state)
100{
101 struct dwc_pwm *dwc = to_dwc_pwm(chip);
102
103 if (state->polarity != PWM_POLARITY_INVERSED)
104 return -EINVAL;
105
106 if (state->enabled) {
107 if (!pwm->state.enabled)
108 pm_runtime_get_sync(pwmchip_parent(chip));
109 return __dwc_pwm_configure_timer(dwc, pwm, state);
110 } else {
111 if (pwm->state.enabled) {
112 __dwc_pwm_set_enable(dwc, pwm->hwpwm, false);
113 pm_runtime_put_sync(pwmchip_parent(chip));
114 }
115 }
116
117 return 0;
118}
119
120static int dwc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
121 struct pwm_state *state)
122{
123 struct dwc_pwm *dwc = to_dwc_pwm(chip);
124 u64 duty, period;
125 u32 ctrl, ld, ld2;
126
127 pm_runtime_get_sync(pwmchip_parent(chip));
128
129 ctrl = dwc_pwm_readl(dwc, DWC_TIM_CTRL(pwm->hwpwm));
130 ld = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT(pwm->hwpwm));
131 ld2 = dwc_pwm_readl(dwc, DWC_TIM_LD_CNT2(pwm->hwpwm));
132
133 state->enabled = !!(ctrl & DWC_TIM_CTRL_EN);
134
135 /*
136 * If we're not in PWM, technically the output is a 50-50
137 * based on the timer load-count only.
138 */
139 if (ctrl & DWC_TIM_CTRL_PWM) {
140 duty = (ld + 1) * dwc->clk_ns;
141 period = (ld2 + 1) * dwc->clk_ns;
142 period += duty;
143 } else {
144 duty = (ld + 1) * dwc->clk_ns;
145 period = duty * 2;
146 }
147
148 state->polarity = PWM_POLARITY_INVERSED;
149 state->period = period;
150 state->duty_cycle = duty;
151
152 pm_runtime_put_sync(pwmchip_parent(chip));
153
154 return 0;
155}
156
157static const struct pwm_ops dwc_pwm_ops = {
158 .apply = dwc_pwm_apply,
159 .get_state = dwc_pwm_get_state,
160};
161
162struct pwm_chip *dwc_pwm_alloc(struct device *dev)
163{
164 struct pwm_chip *chip;
165 struct dwc_pwm *dwc;
166
167 chip = devm_pwmchip_alloc(dev, DWC_TIMERS_TOTAL, sizeof(*dwc));
168 if (IS_ERR(chip))
169 return chip;
170 dwc = to_dwc_pwm(chip);
171
172 dwc->clk_ns = 10;
173 chip->ops = &dwc_pwm_ops;
174
175 return chip;
176}
177EXPORT_SYMBOL_GPL(dwc_pwm_alloc);
178
179MODULE_AUTHOR("Felipe Balbi (Intel)");
180MODULE_AUTHOR("Jarkko Nikula <[email protected]>");
181MODULE_AUTHOR("Raymond Tan <[email protected]>");
182MODULE_DESCRIPTION("DesignWare PWM Controller");
183MODULE_LICENSE("GPL");