1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Intel Keem Bay PWM driver
  4 *
  5 * Copyright (C) 2020 Intel Corporation
  6 * Authors: Lai Poey Seng <poey.seng.lai@intel.com>
  7 *          Vineetha G. Jaya Kumaran <vineetha.g.jaya.kumaran@intel.com>
  8 *
  9 * Limitations:
 10 * - Upon disabling a channel, the currently running
 11 *   period will not be completed. However, upon
 12 *   reconfiguration of the duty cycle/period, the
 13 *   currently running period will be completed first.
 14 */
 15
 16#include <linux/bitfield.h>
 17#include <linux/clk.h>
 18#include <linux/io.h>
 19#include <linux/mod_devicetable.h>
 20#include <linux/module.h>
 21#include <linux/platform_device.h>
 22#include <linux/pwm.h>
 23#include <linux/regmap.h>
 24
 25#define KMB_TOTAL_PWM_CHANNELS		6
 26#define KMB_PWM_COUNT_MAX		U16_MAX
 27#define KMB_PWM_EN_BIT			BIT(31)
 28
 29/* Mask */
 30#define KMB_PWM_HIGH_MASK		GENMASK(31, 16)
 31#define KMB_PWM_LOW_MASK		GENMASK(15, 0)
 32#define KMB_PWM_LEADIN_MASK		GENMASK(30, 0)
 33
 34/* PWM Register offset */
 35#define KMB_PWM_LEADIN_OFFSET(ch)	(0x00 + 4 * (ch))
 36#define KMB_PWM_HIGHLOW_OFFSET(ch)	(0x20 + 4 * (ch))
 37
 38struct keembay_pwm {
 39	struct pwm_chip chip;
 40	struct device *dev;
 41	struct clk *clk;
 42	void __iomem *base;
 43};
 44
 45static inline struct keembay_pwm *to_keembay_pwm_dev(struct pwm_chip *chip)
 46{
 47	return container_of(chip, struct keembay_pwm, chip);
 48}
 49
 50static void keembay_clk_unprepare(void *data)
 51{
 52	clk_disable_unprepare(data);
 53}
 54
 55static int keembay_clk_enable(struct device *dev, struct clk *clk)
 56{
 57	int ret;
 58
 59	ret = clk_prepare_enable(clk);
 60	if (ret)
 61		return ret;
 62
 63	return devm_add_action_or_reset(dev, keembay_clk_unprepare, clk);
 64}
 65
 66/*
 67 * With gcc 10, CONFIG_CC_OPTIMIZE_FOR_SIZE and only "inline" instead of
 68 * "__always_inline" this fails to compile because the compiler doesn't notice
 69 * for all valid masks (e.g. KMB_PWM_LEADIN_MASK) that they are ok.
 70 */
 71static __always_inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32 mask,
 72					   u32 val, u32 offset)
 73{
 74	u32 buff = readl(priv->base + offset);
 75
 76	buff = u32_replace_bits(buff, val, mask);
 77	writel(buff, priv->base + offset);
 78}
 79
 80static void keembay_pwm_enable(struct keembay_pwm *priv, int ch)
 81{
 82	keembay_pwm_update_bits(priv, KMB_PWM_EN_BIT, 1,
 83				KMB_PWM_LEADIN_OFFSET(ch));
 84}
 85
 86static void keembay_pwm_disable(struct keembay_pwm *priv, int ch)
 87{
 88	keembay_pwm_update_bits(priv, KMB_PWM_EN_BIT, 0,
 89				KMB_PWM_LEADIN_OFFSET(ch));
 90}
 91
 92static int keembay_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 93				 struct pwm_state *state)
 94{
 95	struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
 96	unsigned long long high, low;
 97	unsigned long clk_rate;
 98	u32 highlow;
 99
100	clk_rate = clk_get_rate(priv->clk);
101
102	/* Read channel enabled status */
103	highlow = readl(priv->base + KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
104	if (highlow & KMB_PWM_EN_BIT)
105		state->enabled = true;
106	else
107		state->enabled = false;
108
109	/* Read period and duty cycle */
110	highlow = readl(priv->base + KMB_PWM_HIGHLOW_OFFSET(pwm->hwpwm));
111	low = FIELD_GET(KMB_PWM_LOW_MASK, highlow) * NSEC_PER_SEC;
112	high = FIELD_GET(KMB_PWM_HIGH_MASK, highlow) * NSEC_PER_SEC;
113	state->duty_cycle = DIV_ROUND_UP_ULL(high, clk_rate);
114	state->period = DIV_ROUND_UP_ULL(high + low, clk_rate);
115	state->polarity = PWM_POLARITY_NORMAL;
116
117	return 0;
118}
119
120static int keembay_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
121			     const struct pwm_state *state)
122{
123	struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
124	struct pwm_state current_state;
125	unsigned long long div;
126	unsigned long clk_rate;
127	u32 pwm_count = 0;
128	u16 high, low;
129
130	if (state->polarity != PWM_POLARITY_NORMAL)
131		return -EINVAL;
132
133	/*
134	 * Configure the pwm repeat count as infinite at (15:0) and leadin
135	 * low time as 0 at (30:16), which is in terms of clock cycles.
136	 */
137	keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
138				KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
139
140	keembay_pwm_get_state(chip, pwm, &current_state);
141
142	if (!state->enabled) {
143		if (current_state.enabled)
144			keembay_pwm_disable(priv, pwm->hwpwm);
145		return 0;
146	}
147
148	/*
149	 * The upper 16 bits and lower 16 bits of the KMB_PWM_HIGHLOW_OFFSET
150	 * register contain the high time and low time of waveform accordingly.
151	 * All the values are in terms of clock cycles.
152	 */
153
154	clk_rate = clk_get_rate(priv->clk);
155	div = clk_rate * state->duty_cycle;
156	div = DIV_ROUND_DOWN_ULL(div, NSEC_PER_SEC);
157	if (div > KMB_PWM_COUNT_MAX)
158		return -ERANGE;
159
160	high = div;
161	div = clk_rate * state->period;
162	div = DIV_ROUND_DOWN_ULL(div, NSEC_PER_SEC);
163	div = div - high;
164	if (div > KMB_PWM_COUNT_MAX)
165		return -ERANGE;
166
167	low = div;
168
169	pwm_count = FIELD_PREP(KMB_PWM_HIGH_MASK, high) |
170		    FIELD_PREP(KMB_PWM_LOW_MASK, low);
171
172	writel(pwm_count, priv->base + KMB_PWM_HIGHLOW_OFFSET(pwm->hwpwm));
173
174	if (state->enabled && !current_state.enabled)
175		keembay_pwm_enable(priv, pwm->hwpwm);
176
177	return 0;
178}
179
180static const struct pwm_ops keembay_pwm_ops = {
181	.apply = keembay_pwm_apply,
182	.get_state = keembay_pwm_get_state,
183};
184
185static int keembay_pwm_probe(struct platform_device *pdev)
186{
187	struct device *dev = &pdev->dev;
188	struct keembay_pwm *priv;
189	int ret;
190
191	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
192	if (!priv)
193		return -ENOMEM;
194
195	priv->clk = devm_clk_get(dev, NULL);
196	if (IS_ERR(priv->clk))
197		return dev_err_probe(dev, PTR_ERR(priv->clk), "Failed to get clock\n");
198
199	priv->base = devm_platform_ioremap_resource(pdev, 0);
200	if (IS_ERR(priv->base))
201		return PTR_ERR(priv->base);
202
203	ret = keembay_clk_enable(dev, priv->clk);
204	if (ret)
205		return ret;
206
207	priv->chip.dev = dev;
208	priv->chip.ops = &keembay_pwm_ops;
209	priv->chip.npwm = KMB_TOTAL_PWM_CHANNELS;
210
211	ret = devm_pwmchip_add(dev, &priv->chip);
212	if (ret)
213		return dev_err_probe(dev, ret, "Failed to add PWM chip\n");
214
215	return 0;
216}
217
218static const struct of_device_id keembay_pwm_of_match[] = {
219	{ .compatible = "intel,keembay-pwm" },
220	{ }
221};
222MODULE_DEVICE_TABLE(of, keembay_pwm_of_match);
223
224static struct platform_driver keembay_pwm_driver = {
225	.probe	= keembay_pwm_probe,
226	.driver	= {
227		.name = "pwm-keembay",
228		.of_match_table = keembay_pwm_of_match,
229	},
230};
231module_platform_driver(keembay_pwm_driver);
232
233MODULE_ALIAS("platform:pwm-keembay");
234MODULE_DESCRIPTION("Intel Keem Bay PWM driver");
235MODULE_LICENSE("GPL v2");