1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2020 Intel Corporation.
4 *
5 * Limitations:
6 * - The hardware supports fixed period & configures only 2-wire mode.
7 * - Supports normal polarity. Does not support changing polarity.
8 * - When PWM is disabled, output of PWM will become 0(inactive). It doesn't
9 * keep track of running period.
10 * - When duty cycle is changed, PWM output may be a mix of previous setting
11 * and new setting for the first period. From second period, the output is
12 * based on new setting.
13 * - It is a dedicated PWM fan controller. There are no other consumers for
14 * this PWM controller.
15 */
16 #include <linux/bitfield.h>
17 #include <linux/clk.h>
18 #include <linux/module.h>
19 #include <linux/platform_device.h>
20 #include <linux/mod_devicetable.h>
21 #include <linux/pwm.h>
22 #include <linux/regmap.h>
23 #include <linux/reset.h>
24
25 #define LGM_PWM_FAN_CON0 0x0
26 #define LGM_PWM_FAN_EN_EN BIT(0)
27 #define LGM_PWM_FAN_EN_DIS 0x0
28 #define LGM_PWM_FAN_EN_MSK BIT(0)
29 #define LGM_PWM_FAN_MODE_2WIRE 0x0
30 #define LGM_PWM_FAN_MODE_MSK BIT(1)
31 #define LGM_PWM_FAN_DC_MSK GENMASK(23, 16)
32
33 #define LGM_PWM_FAN_CON1 0x4
34 #define LGM_PWM_FAN_MAX_RPM_MSK GENMASK(15, 0)
35
36 #define LGM_PWM_MAX_RPM (BIT(16) - 1)
37 #define LGM_PWM_DEFAULT_RPM 4000
38 #define LGM_PWM_MAX_DUTY_CYCLE (BIT(8) - 1)
39
40 #define LGM_PWM_DC_BITS 8
41
42 #define LGM_PWM_PERIOD_2WIRE_NS (40 * NSEC_PER_MSEC)
43
44 struct lgm_pwm_chip {
45 struct pwm_chip chip;
46 struct regmap *regmap;
47 u32 period;
48 };
49
to_lgm_pwm_chip(struct pwm_chip * chip)50 static inline struct lgm_pwm_chip *to_lgm_pwm_chip(struct pwm_chip *chip)
51 {
52 return container_of(chip, struct lgm_pwm_chip, chip);
53 }
54
lgm_pwm_enable(struct pwm_chip * chip,bool enable)55 static int lgm_pwm_enable(struct pwm_chip *chip, bool enable)
56 {
57 struct lgm_pwm_chip *pc = to_lgm_pwm_chip(chip);
58 struct regmap *regmap = pc->regmap;
59
60 return regmap_update_bits(regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_EN_MSK,
61 enable ? LGM_PWM_FAN_EN_EN : LGM_PWM_FAN_EN_DIS);
62 }
63
lgm_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)64 static int lgm_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
65 const struct pwm_state *state)
66 {
67 struct lgm_pwm_chip *pc = to_lgm_pwm_chip(chip);
68 u32 duty_cycle, val;
69 int ret;
70
71 /* The hardware only supports normal polarity and fixed period. */
72 if (state->polarity != PWM_POLARITY_NORMAL || state->period < pc->period)
73 return -EINVAL;
74
75 if (!state->enabled)
76 return lgm_pwm_enable(chip, 0);
77
78 duty_cycle = min_t(u64, state->duty_cycle, pc->period);
79 val = duty_cycle * LGM_PWM_MAX_DUTY_CYCLE / pc->period;
80
81 ret = regmap_update_bits(pc->regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_DC_MSK,
82 FIELD_PREP(LGM_PWM_FAN_DC_MSK, val));
83 if (ret)
84 return ret;
85
86 return lgm_pwm_enable(chip, 1);
87 }
88
lgm_pwm_get_state(struct pwm_chip * chip,struct pwm_device * pwm,struct pwm_state * state)89 static void lgm_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
90 struct pwm_state *state)
91 {
92 struct lgm_pwm_chip *pc = to_lgm_pwm_chip(chip);
93 u32 duty, val;
94
95 state->enabled = regmap_test_bits(pc->regmap, LGM_PWM_FAN_CON0,
96 LGM_PWM_FAN_EN_EN);
97 state->polarity = PWM_POLARITY_NORMAL;
98 state->period = pc->period; /* fixed period */
99
100 regmap_read(pc->regmap, LGM_PWM_FAN_CON0, &val);
101 duty = FIELD_GET(LGM_PWM_FAN_DC_MSK, val);
102 state->duty_cycle = DIV_ROUND_UP(duty * pc->period, LGM_PWM_MAX_DUTY_CYCLE);
103 }
104
105 static const struct pwm_ops lgm_pwm_ops = {
106 .get_state = lgm_pwm_get_state,
107 .apply = lgm_pwm_apply,
108 .owner = THIS_MODULE,
109 };
110
lgm_pwm_init(struct lgm_pwm_chip * pc)111 static void lgm_pwm_init(struct lgm_pwm_chip *pc)
112 {
113 struct regmap *regmap = pc->regmap;
114 u32 con0_val;
115
116 con0_val = FIELD_PREP(LGM_PWM_FAN_MODE_MSK, LGM_PWM_FAN_MODE_2WIRE);
117 pc->period = LGM_PWM_PERIOD_2WIRE_NS;
118 regmap_update_bits(regmap, LGM_PWM_FAN_CON1, LGM_PWM_FAN_MAX_RPM_MSK,
119 LGM_PWM_DEFAULT_RPM);
120 regmap_update_bits(regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_MODE_MSK,
121 con0_val);
122 }
123
124 static const struct regmap_config lgm_pwm_regmap_config = {
125 .reg_bits = 32,
126 .reg_stride = 4,
127 .val_bits = 32,
128 };
129
lgm_clk_release(void * data)130 static void lgm_clk_release(void *data)
131 {
132 struct clk *clk = data;
133
134 clk_disable_unprepare(clk);
135 }
136
lgm_clk_enable(struct device * dev,struct clk * clk)137 static int lgm_clk_enable(struct device *dev, struct clk *clk)
138 {
139 int ret;
140
141 ret = clk_prepare_enable(clk);
142 if (ret)
143 return ret;
144
145 return devm_add_action_or_reset(dev, lgm_clk_release, clk);
146 }
147
lgm_reset_control_release(void * data)148 static void lgm_reset_control_release(void *data)
149 {
150 struct reset_control *rst = data;
151
152 reset_control_assert(rst);
153 }
154
lgm_reset_control_deassert(struct device * dev,struct reset_control * rst)155 static int lgm_reset_control_deassert(struct device *dev, struct reset_control *rst)
156 {
157 int ret;
158
159 ret = reset_control_deassert(rst);
160 if (ret)
161 return ret;
162
163 return devm_add_action_or_reset(dev, lgm_reset_control_release, rst);
164 }
165
lgm_pwm_probe(struct platform_device * pdev)166 static int lgm_pwm_probe(struct platform_device *pdev)
167 {
168 struct device *dev = &pdev->dev;
169 struct reset_control *rst;
170 struct lgm_pwm_chip *pc;
171 void __iomem *io_base;
172 struct clk *clk;
173 int ret;
174
175 pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
176 if (!pc)
177 return -ENOMEM;
178
179 platform_set_drvdata(pdev, pc);
180
181 io_base = devm_platform_ioremap_resource(pdev, 0);
182 if (IS_ERR(io_base))
183 return PTR_ERR(io_base);
184
185 pc->regmap = devm_regmap_init_mmio(dev, io_base, &lgm_pwm_regmap_config);
186 if (IS_ERR(pc->regmap))
187 return dev_err_probe(dev, PTR_ERR(pc->regmap),
188 "failed to init register map\n");
189
190 clk = devm_clk_get(dev, NULL);
191 if (IS_ERR(clk))
192 return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
193
194 ret = lgm_clk_enable(dev, clk);
195 if (ret)
196 return dev_err_probe(dev, ret, "failed to enable clock\n");
197
198 rst = devm_reset_control_get_exclusive(dev, NULL);
199 if (IS_ERR(rst))
200 return dev_err_probe(dev, PTR_ERR(rst),
201 "failed to get reset control\n");
202
203 ret = lgm_reset_control_deassert(dev, rst);
204 if (ret)
205 return dev_err_probe(dev, ret, "cannot deassert reset control\n");
206
207 pc->chip.dev = dev;
208 pc->chip.ops = &lgm_pwm_ops;
209 pc->chip.npwm = 1;
210
211 lgm_pwm_init(pc);
212
213 ret = pwmchip_add(&pc->chip);
214 if (ret < 0)
215 return dev_err_probe(dev, ret, "failed to add PWM chip\n");
216
217 return 0;
218 }
219
lgm_pwm_remove(struct platform_device * pdev)220 static int lgm_pwm_remove(struct platform_device *pdev)
221 {
222 struct lgm_pwm_chip *pc = platform_get_drvdata(pdev);
223
224 return pwmchip_remove(&pc->chip);
225 }
226
227 static const struct of_device_id lgm_pwm_of_match[] = {
228 { .compatible = "intel,lgm-pwm" },
229 { }
230 };
231 MODULE_DEVICE_TABLE(of, lgm_pwm_of_match);
232
233 static struct platform_driver lgm_pwm_driver = {
234 .driver = {
235 .name = "intel-pwm",
236 .of_match_table = lgm_pwm_of_match,
237 },
238 .probe = lgm_pwm_probe,
239 .remove = lgm_pwm_remove,
240 };
241 module_platform_driver(lgm_pwm_driver);
242
243 MODULE_LICENSE("GPL v2");
244