1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2019 Spreadtrum Communications Inc. 4 */ 5 6 #include <linux/clk.h> 7 #include <linux/err.h> 8 #include <linux/io.h> 9 #include <linux/math64.h> 10 #include <linux/module.h> 11 #include <linux/platform_device.h> 12 #include <linux/pwm.h> 13 14 #define SPRD_PWM_PRESCALE 0x0 15 #define SPRD_PWM_MOD 0x4 16 #define SPRD_PWM_DUTY 0x8 17 #define SPRD_PWM_ENABLE 0x18 18 19 #define SPRD_PWM_MOD_MAX GENMASK(7, 0) 20 #define SPRD_PWM_DUTY_MSK GENMASK(15, 0) 21 #define SPRD_PWM_PRESCALE_MSK GENMASK(7, 0) 22 #define SPRD_PWM_ENABLE_BIT BIT(0) 23 24 #define SPRD_PWM_CHN_NUM 4 25 #define SPRD_PWM_REGS_SHIFT 5 26 #define SPRD_PWM_CHN_CLKS_NUM 2 27 #define SPRD_PWM_CHN_OUTPUT_CLK 1 28 29 struct sprd_pwm_chn { 30 struct clk_bulk_data clks[SPRD_PWM_CHN_CLKS_NUM]; 31 u32 clk_rate; 32 }; 33 34 struct sprd_pwm_chip { 35 void __iomem *base; 36 struct device *dev; 37 struct pwm_chip chip; 38 int num_pwms; 39 struct sprd_pwm_chn chn[SPRD_PWM_CHN_NUM]; 40 }; 41 42 /* 43 * The list of clocks required by PWM channels, and each channel has 2 clocks: 44 * enable clock and pwm clock. 45 */ 46 static const char * const sprd_pwm_clks[] = { 47 "enable0", "pwm0", 48 "enable1", "pwm1", 49 "enable2", "pwm2", 50 "enable3", "pwm3", 51 }; 52 53 static u32 sprd_pwm_read(struct sprd_pwm_chip *spc, u32 hwid, u32 reg) 54 { 55 u32 offset = reg + (hwid << SPRD_PWM_REGS_SHIFT); 56 57 return readl_relaxed(spc->base + offset); 58 } 59 60 static void sprd_pwm_write(struct sprd_pwm_chip *spc, u32 hwid, 61 u32 reg, u32 val) 62 { 63 u32 offset = reg + (hwid << SPRD_PWM_REGS_SHIFT); 64 65 writel_relaxed(val, spc->base + offset); 66 } 67 68 static void sprd_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 69 struct pwm_state *state) 70 { 71 struct sprd_pwm_chip *spc = 72 container_of(chip, struct sprd_pwm_chip, chip); 73 struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm]; 74 u32 val, duty, prescale; 75 u64 tmp; 76 int ret; 77 78 /* 79 * The clocks to PWM channel has to be enabled first before 80 * reading to the registers. 81 */ 82 ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM, chn->clks); 83 if (ret) { 84 dev_err(spc->dev, "failed to enable pwm%u clocks\n", 85 pwm->hwpwm); 86 return; 87 } 88 89 val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_ENABLE); 90 if (val & SPRD_PWM_ENABLE_BIT) 91 state->enabled = true; 92 else 93 state->enabled = false; 94 95 /* 96 * The hardware provides a counter that is feed by the source clock. 97 * The period length is (PRESCALE + 1) * MOD counter steps. 98 * The duty cycle length is (PRESCALE + 1) * DUTY counter steps. 99 * Thus the period_ns and duty_ns calculation formula should be: 100 * period_ns = NSEC_PER_SEC * (prescale + 1) * mod / clk_rate 101 * duty_ns = NSEC_PER_SEC * (prescale + 1) * duty / clk_rate 102 */ 103 val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_PRESCALE); 104 prescale = val & SPRD_PWM_PRESCALE_MSK; 105 tmp = (prescale + 1) * NSEC_PER_SEC * SPRD_PWM_MOD_MAX; 106 state->period = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate); 107 108 val = sprd_pwm_read(spc, pwm->hwpwm, SPRD_PWM_DUTY); 109 duty = val & SPRD_PWM_DUTY_MSK; 110 tmp = (prescale + 1) * NSEC_PER_SEC * duty; 111 state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, chn->clk_rate); 112 113 /* Disable PWM clocks if the PWM channel is not in enable state. */ 114 if (!state->enabled) 115 clk_bulk_disable_unprepare(SPRD_PWM_CHN_CLKS_NUM, chn->clks); 116 } 117 118 static int sprd_pwm_config(struct sprd_pwm_chip *spc, struct pwm_device *pwm, 119 int duty_ns, int period_ns) 120 { 121 struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm]; 122 u32 prescale, duty; 123 u64 tmp; 124 125 /* 126 * The hardware provides a counter that is feed by the source clock. 127 * The period length is (PRESCALE + 1) * MOD counter steps. 128 * The duty cycle length is (PRESCALE + 1) * DUTY counter steps. 129 * 130 * To keep the maths simple we're always using MOD = SPRD_PWM_MOD_MAX. 131 * The value for PRESCALE is selected such that the resulting period 132 * gets the maximal length not bigger than the requested one with the 133 * given settings (MOD = SPRD_PWM_MOD_MAX and input clock). 134 */ 135 duty = duty_ns * SPRD_PWM_MOD_MAX / period_ns; 136 137 tmp = (u64)chn->clk_rate * period_ns; 138 do_div(tmp, NSEC_PER_SEC); 139 prescale = DIV_ROUND_CLOSEST_ULL(tmp, SPRD_PWM_MOD_MAX) - 1; 140 if (prescale > SPRD_PWM_PRESCALE_MSK) 141 prescale = SPRD_PWM_PRESCALE_MSK; 142 143 /* 144 * Note: Writing DUTY triggers the hardware to actually apply the 145 * values written to MOD and DUTY to the output, so must keep writing 146 * DUTY last. 147 * 148 * The hardware can ensures that current running period is completed 149 * before changing a new configuration to avoid mixed settings. 150 */ 151 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_PRESCALE, prescale); 152 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_MOD, SPRD_PWM_MOD_MAX); 153 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_DUTY, duty); 154 155 return 0; 156 } 157 158 static int sprd_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 159 const struct pwm_state *state) 160 { 161 struct sprd_pwm_chip *spc = 162 container_of(chip, struct sprd_pwm_chip, chip); 163 struct sprd_pwm_chn *chn = &spc->chn[pwm->hwpwm]; 164 struct pwm_state *cstate = &pwm->state; 165 int ret; 166 167 if (state->enabled) { 168 if (!cstate->enabled) { 169 /* 170 * The clocks to PWM channel has to be enabled first 171 * before writing to the registers. 172 */ 173 ret = clk_bulk_prepare_enable(SPRD_PWM_CHN_CLKS_NUM, 174 chn->clks); 175 if (ret) { 176 dev_err(spc->dev, 177 "failed to enable pwm%u clocks\n", 178 pwm->hwpwm); 179 return ret; 180 } 181 } 182 183 if (state->period != cstate->period || 184 state->duty_cycle != cstate->duty_cycle) { 185 ret = sprd_pwm_config(spc, pwm, state->duty_cycle, 186 state->period); 187 if (ret) 188 return ret; 189 } 190 191 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_ENABLE, 1); 192 } else if (cstate->enabled) { 193 /* 194 * Note: After setting SPRD_PWM_ENABLE to zero, the controller 195 * will not wait for current period to be completed, instead it 196 * will stop the PWM channel immediately. 197 */ 198 sprd_pwm_write(spc, pwm->hwpwm, SPRD_PWM_ENABLE, 0); 199 200 clk_bulk_disable_unprepare(SPRD_PWM_CHN_CLKS_NUM, chn->clks); 201 } 202 203 return 0; 204 } 205 206 static const struct pwm_ops sprd_pwm_ops = { 207 .apply = sprd_pwm_apply, 208 .get_state = sprd_pwm_get_state, 209 .owner = THIS_MODULE, 210 }; 211 212 static int sprd_pwm_clk_init(struct sprd_pwm_chip *spc) 213 { 214 struct clk *clk_pwm; 215 int ret, i; 216 217 for (i = 0; i < SPRD_PWM_CHN_NUM; i++) { 218 struct sprd_pwm_chn *chn = &spc->chn[i]; 219 int j; 220 221 for (j = 0; j < SPRD_PWM_CHN_CLKS_NUM; ++j) 222 chn->clks[j].id = 223 sprd_pwm_clks[i * SPRD_PWM_CHN_CLKS_NUM + j]; 224 225 ret = devm_clk_bulk_get(spc->dev, SPRD_PWM_CHN_CLKS_NUM, 226 chn->clks); 227 if (ret) { 228 if (ret == -ENOENT) 229 break; 230 231 return dev_err_probe(spc->dev, ret, 232 "failed to get channel clocks\n"); 233 } 234 235 clk_pwm = chn->clks[SPRD_PWM_CHN_OUTPUT_CLK].clk; 236 chn->clk_rate = clk_get_rate(clk_pwm); 237 } 238 239 if (!i) { 240 dev_err(spc->dev, "no available PWM channels\n"); 241 return -ENODEV; 242 } 243 244 spc->num_pwms = i; 245 246 return 0; 247 } 248 249 static int sprd_pwm_probe(struct platform_device *pdev) 250 { 251 struct sprd_pwm_chip *spc; 252 int ret; 253 254 spc = devm_kzalloc(&pdev->dev, sizeof(*spc), GFP_KERNEL); 255 if (!spc) 256 return -ENOMEM; 257 258 spc->base = devm_platform_ioremap_resource(pdev, 0); 259 if (IS_ERR(spc->base)) 260 return PTR_ERR(spc->base); 261 262 spc->dev = &pdev->dev; 263 platform_set_drvdata(pdev, spc); 264 265 ret = sprd_pwm_clk_init(spc); 266 if (ret) 267 return ret; 268 269 spc->chip.dev = &pdev->dev; 270 spc->chip.ops = &sprd_pwm_ops; 271 spc->chip.base = -1; 272 spc->chip.npwm = spc->num_pwms; 273 274 ret = pwmchip_add(&spc->chip); 275 if (ret) 276 dev_err(&pdev->dev, "failed to add PWM chip\n"); 277 278 return ret; 279 } 280 281 static int sprd_pwm_remove(struct platform_device *pdev) 282 { 283 struct sprd_pwm_chip *spc = platform_get_drvdata(pdev); 284 285 return pwmchip_remove(&spc->chip); 286 } 287 288 static const struct of_device_id sprd_pwm_of_match[] = { 289 { .compatible = "sprd,ums512-pwm", }, 290 { }, 291 }; 292 MODULE_DEVICE_TABLE(of, sprd_pwm_of_match); 293 294 static struct platform_driver sprd_pwm_driver = { 295 .driver = { 296 .name = "sprd-pwm", 297 .of_match_table = sprd_pwm_of_match, 298 }, 299 .probe = sprd_pwm_probe, 300 .remove = sprd_pwm_remove, 301 }; 302 303 module_platform_driver(sprd_pwm_driver); 304 305 MODULE_DESCRIPTION("Spreadtrum PWM Driver"); 306 MODULE_LICENSE("GPL v2"); 307