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 #include <linux/delay.h> 14 #include <linux/io.h> 15 #include <linux/iopoll.h> 16 #include <linux/kernel.h> 17 #include <linux/module.h> 18 #include <linux/pm_runtime.h> 19 #include <linux/time.h> 20 21 #include "pwm-lpss.h" 22 23 #define PWM 0x00000000 24 #define PWM_ENABLE BIT(31) 25 #define PWM_SW_UPDATE BIT(30) 26 #define PWM_BASE_UNIT_SHIFT 8 27 #define PWM_ON_TIME_DIV_MASK 0x000000ff 28 29 /* Size of each PWM register space if multiple */ 30 #define PWM_SIZE 0x400 31 32 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip) 33 { 34 return container_of(chip, struct pwm_lpss_chip, chip); 35 } 36 37 static inline u32 pwm_lpss_read(const struct pwm_device *pwm) 38 { 39 struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip); 40 41 return readl(lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM); 42 } 43 44 static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value) 45 { 46 struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip); 47 48 writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM); 49 } 50 51 static int pwm_lpss_wait_for_update(struct pwm_device *pwm) 52 { 53 struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip); 54 const void __iomem *addr = lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM; 55 const unsigned int ms = 500 * USEC_PER_MSEC; 56 u32 val; 57 int err; 58 59 /* 60 * PWM Configuration register has SW_UPDATE bit that is set when a new 61 * configuration is written to the register. The bit is automatically 62 * cleared at the start of the next output cycle by the IP block. 63 * 64 * If one writes a new configuration to the register while it still has 65 * the bit enabled, PWM may freeze. That is, while one can still write 66 * to the register, it won't have an effect. Thus, we try to sleep long 67 * enough that the bit gets cleared and make sure the bit is not 68 * enabled while we update the configuration. 69 */ 70 err = readl_poll_timeout(addr, val, !(val & PWM_SW_UPDATE), 40, ms); 71 if (err) 72 dev_err(pwm->chip->dev, "PWM_SW_UPDATE was not cleared\n"); 73 74 return err; 75 } 76 77 static inline int pwm_lpss_is_updating(struct pwm_device *pwm) 78 { 79 if (pwm_lpss_read(pwm) & PWM_SW_UPDATE) { 80 dev_err(pwm->chip->dev, "PWM_SW_UPDATE is still set, skipping update\n"); 81 return -EBUSY; 82 } 83 84 return 0; 85 } 86 87 static void pwm_lpss_prepare(struct pwm_lpss_chip *lpwm, struct pwm_device *pwm, 88 int duty_ns, int period_ns) 89 { 90 unsigned long long on_time_div; 91 unsigned long c = lpwm->info->clk_rate, base_unit_range; 92 unsigned long long base_unit, freq = NSEC_PER_SEC; 93 u32 ctrl; 94 95 do_div(freq, period_ns); 96 97 /* 98 * The equation is: 99 * base_unit = round(base_unit_range * freq / c) 100 */ 101 base_unit_range = BIT(lpwm->info->base_unit_bits); 102 freq *= base_unit_range; 103 104 base_unit = DIV_ROUND_CLOSEST_ULL(freq, c); 105 /* base_unit must not be 0 and we also want to avoid overflowing it */ 106 base_unit = clamp_val(base_unit, 1, base_unit_range - 1); 107 108 on_time_div = 255ULL * duty_ns; 109 do_div(on_time_div, period_ns); 110 on_time_div = 255ULL - on_time_div; 111 112 ctrl = pwm_lpss_read(pwm); 113 ctrl &= ~PWM_ON_TIME_DIV_MASK; 114 ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT); 115 ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT; 116 ctrl |= on_time_div; 117 118 pwm_lpss_write(pwm, ctrl); 119 pwm_lpss_write(pwm, ctrl | PWM_SW_UPDATE); 120 } 121 122 static inline void pwm_lpss_cond_enable(struct pwm_device *pwm, bool cond) 123 { 124 if (cond) 125 pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE); 126 } 127 128 static int pwm_lpss_prepare_enable(struct pwm_lpss_chip *lpwm, 129 struct pwm_device *pwm, 130 const struct pwm_state *state) 131 { 132 int ret; 133 134 ret = pwm_lpss_is_updating(pwm); 135 if (ret) 136 return ret; 137 138 pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period); 139 pwm_lpss_cond_enable(pwm, lpwm->info->bypass == false); 140 ret = pwm_lpss_wait_for_update(pwm); 141 if (ret) 142 return ret; 143 144 pwm_lpss_cond_enable(pwm, lpwm->info->bypass == true); 145 return 0; 146 } 147 148 static int pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm, 149 const struct pwm_state *state) 150 { 151 struct pwm_lpss_chip *lpwm = to_lpwm(chip); 152 int ret = 0; 153 154 if (state->enabled) { 155 if (!pwm_is_enabled(pwm)) { 156 pm_runtime_get_sync(chip->dev); 157 ret = pwm_lpss_prepare_enable(lpwm, pwm, state); 158 if (ret) 159 pm_runtime_put(chip->dev); 160 } else { 161 ret = pwm_lpss_prepare_enable(lpwm, pwm, state); 162 } 163 } else if (pwm_is_enabled(pwm)) { 164 pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE); 165 pm_runtime_put(chip->dev); 166 } 167 168 return ret; 169 } 170 171 static void pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 172 struct pwm_state *state) 173 { 174 struct pwm_lpss_chip *lpwm = to_lpwm(chip); 175 unsigned long base_unit_range; 176 unsigned long long base_unit, freq, on_time_div; 177 u32 ctrl; 178 179 pm_runtime_get_sync(chip->dev); 180 181 base_unit_range = BIT(lpwm->info->base_unit_bits); 182 183 ctrl = pwm_lpss_read(pwm); 184 on_time_div = 255 - (ctrl & PWM_ON_TIME_DIV_MASK); 185 base_unit = (ctrl >> PWM_BASE_UNIT_SHIFT) & (base_unit_range - 1); 186 187 freq = base_unit * lpwm->info->clk_rate; 188 do_div(freq, base_unit_range); 189 if (freq == 0) 190 state->period = NSEC_PER_SEC; 191 else 192 state->period = NSEC_PER_SEC / (unsigned long)freq; 193 194 on_time_div *= state->period; 195 do_div(on_time_div, 255); 196 state->duty_cycle = on_time_div; 197 198 state->polarity = PWM_POLARITY_NORMAL; 199 state->enabled = !!(ctrl & PWM_ENABLE); 200 201 pm_runtime_put(chip->dev); 202 } 203 204 static const struct pwm_ops pwm_lpss_ops = { 205 .apply = pwm_lpss_apply, 206 .get_state = pwm_lpss_get_state, 207 .owner = THIS_MODULE, 208 }; 209 210 struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r, 211 const struct pwm_lpss_boardinfo *info) 212 { 213 struct pwm_lpss_chip *lpwm; 214 unsigned long c; 215 int i, ret; 216 u32 ctrl; 217 218 if (WARN_ON(info->npwm > MAX_PWMS)) 219 return ERR_PTR(-ENODEV); 220 221 lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL); 222 if (!lpwm) 223 return ERR_PTR(-ENOMEM); 224 225 lpwm->regs = devm_ioremap_resource(dev, r); 226 if (IS_ERR(lpwm->regs)) 227 return ERR_CAST(lpwm->regs); 228 229 lpwm->info = info; 230 231 c = lpwm->info->clk_rate; 232 if (!c) 233 return ERR_PTR(-EINVAL); 234 235 lpwm->chip.dev = dev; 236 lpwm->chip.ops = &pwm_lpss_ops; 237 lpwm->chip.npwm = info->npwm; 238 239 ret = pwmchip_add(&lpwm->chip); 240 if (ret) { 241 dev_err(dev, "failed to add PWM chip: %d\n", ret); 242 return ERR_PTR(ret); 243 } 244 245 for (i = 0; i < lpwm->info->npwm; i++) { 246 ctrl = pwm_lpss_read(&lpwm->chip.pwms[i]); 247 if (ctrl & PWM_ENABLE) 248 pm_runtime_get(dev); 249 } 250 251 return lpwm; 252 } 253 EXPORT_SYMBOL_GPL(pwm_lpss_probe); 254 255 int pwm_lpss_remove(struct pwm_lpss_chip *lpwm) 256 { 257 return pwmchip_remove(&lpwm->chip); 258 } 259 EXPORT_SYMBOL_GPL(pwm_lpss_remove); 260 261 MODULE_DESCRIPTION("PWM driver for Intel LPSS"); 262 MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>"); 263 MODULE_LICENSE("GPL v2"); 264