1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Expose a PWM controlled by the ChromeOS EC to the host processor. 4 * 5 * Copyright (C) 2016 Google, Inc. 6 */ 7 8 #include <linux/module.h> 9 #include <linux/of.h> 10 #include <linux/platform_data/cros_ec_commands.h> 11 #include <linux/platform_data/cros_ec_proto.h> 12 #include <linux/platform_device.h> 13 #include <linux/pwm.h> 14 #include <linux/slab.h> 15 16 #include <dt-bindings/mfd/cros_ec.h> 17 18 /** 19 * struct cros_ec_pwm_device - Driver data for EC PWM 20 * 21 * @dev: Device node 22 * @ec: Pointer to EC device 23 * @chip: PWM controller chip 24 * @use_pwm_type: Use PWM types instead of generic channels 25 */ 26 struct cros_ec_pwm_device { 27 struct device *dev; 28 struct cros_ec_device *ec; 29 struct pwm_chip chip; 30 bool use_pwm_type; 31 }; 32 33 /** 34 * struct cros_ec_pwm - per-PWM driver data 35 * @duty_cycle: cached duty cycle 36 */ 37 struct cros_ec_pwm { 38 u16 duty_cycle; 39 }; 40 41 static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *chip) 42 { 43 return container_of(chip, struct cros_ec_pwm_device, chip); 44 } 45 46 static int cros_ec_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) 47 { 48 struct cros_ec_pwm *channel; 49 50 channel = kzalloc(sizeof(*channel), GFP_KERNEL); 51 if (!channel) 52 return -ENOMEM; 53 54 pwm_set_chip_data(pwm, channel); 55 56 return 0; 57 } 58 59 static void cros_ec_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) 60 { 61 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm); 62 63 kfree(channel); 64 } 65 66 static int cros_ec_dt_type_to_pwm_type(u8 dt_index, u8 *pwm_type) 67 { 68 switch (dt_index) { 69 case CROS_EC_PWM_DT_KB_LIGHT: 70 *pwm_type = EC_PWM_TYPE_KB_LIGHT; 71 return 0; 72 case CROS_EC_PWM_DT_DISPLAY_LIGHT: 73 *pwm_type = EC_PWM_TYPE_DISPLAY_LIGHT; 74 return 0; 75 default: 76 return -EINVAL; 77 } 78 } 79 80 static int cros_ec_pwm_set_duty(struct cros_ec_pwm_device *ec_pwm, u8 index, 81 u16 duty) 82 { 83 struct cros_ec_device *ec = ec_pwm->ec; 84 struct { 85 struct cros_ec_command msg; 86 struct ec_params_pwm_set_duty params; 87 } __packed buf; 88 struct ec_params_pwm_set_duty *params = &buf.params; 89 struct cros_ec_command *msg = &buf.msg; 90 int ret; 91 92 memset(&buf, 0, sizeof(buf)); 93 94 msg->version = 0; 95 msg->command = EC_CMD_PWM_SET_DUTY; 96 msg->insize = 0; 97 msg->outsize = sizeof(*params); 98 99 params->duty = duty; 100 101 if (ec_pwm->use_pwm_type) { 102 ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type); 103 if (ret) { 104 dev_err(ec->dev, "Invalid PWM type index: %d\n", index); 105 return ret; 106 } 107 params->index = 0; 108 } else { 109 params->pwm_type = EC_PWM_TYPE_GENERIC; 110 params->index = index; 111 } 112 113 return cros_ec_cmd_xfer_status(ec, msg); 114 } 115 116 static int cros_ec_pwm_get_duty(struct cros_ec_pwm_device *ec_pwm, u8 index) 117 { 118 struct cros_ec_device *ec = ec_pwm->ec; 119 struct { 120 struct cros_ec_command msg; 121 union { 122 struct ec_params_pwm_get_duty params; 123 struct ec_response_pwm_get_duty resp; 124 }; 125 } __packed buf; 126 struct ec_params_pwm_get_duty *params = &buf.params; 127 struct ec_response_pwm_get_duty *resp = &buf.resp; 128 struct cros_ec_command *msg = &buf.msg; 129 int ret; 130 131 memset(&buf, 0, sizeof(buf)); 132 133 msg->version = 0; 134 msg->command = EC_CMD_PWM_GET_DUTY; 135 msg->insize = sizeof(*resp); 136 msg->outsize = sizeof(*params); 137 138 if (ec_pwm->use_pwm_type) { 139 ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type); 140 if (ret) { 141 dev_err(ec->dev, "Invalid PWM type index: %d\n", index); 142 return ret; 143 } 144 params->index = 0; 145 } else { 146 params->pwm_type = EC_PWM_TYPE_GENERIC; 147 params->index = index; 148 } 149 150 ret = cros_ec_cmd_xfer_status(ec, msg); 151 if (ret < 0) 152 return ret; 153 154 return resp->duty; 155 } 156 157 static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 158 const struct pwm_state *state) 159 { 160 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 161 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm); 162 u16 duty_cycle; 163 int ret; 164 165 /* The EC won't let us change the period */ 166 if (state->period != EC_PWM_MAX_DUTY) 167 return -EINVAL; 168 169 if (state->polarity != PWM_POLARITY_NORMAL) 170 return -EINVAL; 171 172 /* 173 * EC doesn't separate the concept of duty cycle and enabled, but 174 * kernel does. Translate. 175 */ 176 duty_cycle = state->enabled ? state->duty_cycle : 0; 177 178 ret = cros_ec_pwm_set_duty(ec_pwm, pwm->hwpwm, duty_cycle); 179 if (ret < 0) 180 return ret; 181 182 channel->duty_cycle = state->duty_cycle; 183 184 return 0; 185 } 186 187 static int cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 188 struct pwm_state *state) 189 { 190 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 191 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm); 192 int ret; 193 194 ret = cros_ec_pwm_get_duty(ec_pwm, pwm->hwpwm); 195 if (ret < 0) { 196 dev_err(chip->dev, "error getting initial duty: %d\n", ret); 197 return ret; 198 } 199 200 state->enabled = (ret > 0); 201 state->period = EC_PWM_MAX_DUTY; 202 state->polarity = PWM_POLARITY_NORMAL; 203 204 /* 205 * Note that "disabled" and "duty cycle == 0" are treated the same. If 206 * the cached duty cycle is not zero, used the cached duty cycle. This 207 * ensures that the configured duty cycle is kept across a disable and 208 * enable operation and avoids potentially confusing consumers. 209 * 210 * For the case of the initial hardware readout, channel->duty_cycle 211 * will be 0 and the actual duty cycle read from the EC is used. 212 */ 213 if (ret == 0 && channel->duty_cycle > 0) 214 state->duty_cycle = channel->duty_cycle; 215 else 216 state->duty_cycle = ret; 217 218 return 0; 219 } 220 221 static struct pwm_device * 222 cros_ec_pwm_xlate(struct pwm_chip *chip, const struct of_phandle_args *args) 223 { 224 struct pwm_device *pwm; 225 226 if (args->args[0] >= chip->npwm) 227 return ERR_PTR(-EINVAL); 228 229 pwm = pwm_request_from_chip(chip, args->args[0], NULL); 230 if (IS_ERR(pwm)) 231 return pwm; 232 233 /* The EC won't let us change the period */ 234 pwm->args.period = EC_PWM_MAX_DUTY; 235 236 return pwm; 237 } 238 239 static const struct pwm_ops cros_ec_pwm_ops = { 240 .request = cros_ec_pwm_request, 241 .free = cros_ec_pwm_free, 242 .get_state = cros_ec_pwm_get_state, 243 .apply = cros_ec_pwm_apply, 244 .owner = THIS_MODULE, 245 }; 246 247 /* 248 * Determine the number of supported PWMs. The EC does not return the number 249 * of PWMs it supports directly, so we have to read the pwm duty cycle for 250 * subsequent channels until we get an error. 251 */ 252 static int cros_ec_num_pwms(struct cros_ec_pwm_device *ec_pwm) 253 { 254 int i, ret; 255 256 /* The index field is only 8 bits */ 257 for (i = 0; i <= U8_MAX; i++) { 258 ret = cros_ec_pwm_get_duty(ec_pwm, i); 259 /* 260 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM 261 * responses; everything else is treated as an error. 262 * The EC error codes map to -EOPNOTSUPP and -EINVAL, 263 * so check for those. 264 */ 265 switch (ret) { 266 case -EOPNOTSUPP: /* invalid command */ 267 return -ENODEV; 268 case -EINVAL: /* invalid parameter */ 269 return i; 270 default: 271 if (ret < 0) 272 return ret; 273 break; 274 } 275 } 276 277 return U8_MAX; 278 } 279 280 static int cros_ec_pwm_probe(struct platform_device *pdev) 281 { 282 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); 283 struct device *dev = &pdev->dev; 284 struct device_node *np = pdev->dev.of_node; 285 struct cros_ec_pwm_device *ec_pwm; 286 struct pwm_chip *chip; 287 int ret; 288 289 if (!ec) { 290 dev_err(dev, "no parent EC device\n"); 291 return -EINVAL; 292 } 293 294 ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL); 295 if (!ec_pwm) 296 return -ENOMEM; 297 chip = &ec_pwm->chip; 298 ec_pwm->ec = ec; 299 300 if (of_device_is_compatible(np, "google,cros-ec-pwm-type")) 301 ec_pwm->use_pwm_type = true; 302 303 /* PWM chip */ 304 chip->dev = dev; 305 chip->ops = &cros_ec_pwm_ops; 306 chip->of_xlate = cros_ec_pwm_xlate; 307 chip->of_pwm_n_cells = 1; 308 309 if (ec_pwm->use_pwm_type) { 310 chip->npwm = CROS_EC_PWM_DT_COUNT; 311 } else { 312 ret = cros_ec_num_pwms(ec_pwm); 313 if (ret < 0) { 314 dev_err(dev, "Couldn't find PWMs: %d\n", ret); 315 return ret; 316 } 317 chip->npwm = ret; 318 } 319 320 dev_dbg(dev, "Probed %u PWMs\n", chip->npwm); 321 322 ret = pwmchip_add(chip); 323 if (ret < 0) { 324 dev_err(dev, "cannot register PWM: %d\n", ret); 325 return ret; 326 } 327 328 platform_set_drvdata(pdev, ec_pwm); 329 330 return ret; 331 } 332 333 static void cros_ec_pwm_remove(struct platform_device *dev) 334 { 335 struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev); 336 struct pwm_chip *chip = &ec_pwm->chip; 337 338 pwmchip_remove(chip); 339 } 340 341 #ifdef CONFIG_OF 342 static const struct of_device_id cros_ec_pwm_of_match[] = { 343 { .compatible = "google,cros-ec-pwm" }, 344 { .compatible = "google,cros-ec-pwm-type" }, 345 {}, 346 }; 347 MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match); 348 #endif 349 350 static struct platform_driver cros_ec_pwm_driver = { 351 .probe = cros_ec_pwm_probe, 352 .remove_new = cros_ec_pwm_remove, 353 .driver = { 354 .name = "cros-ec-pwm", 355 .of_match_table = of_match_ptr(cros_ec_pwm_of_match), 356 }, 357 }; 358 module_platform_driver(cros_ec_pwm_driver); 359 360 MODULE_ALIAS("platform:cros-ec-pwm"); 361 MODULE_DESCRIPTION("ChromeOS EC PWM driver"); 362 MODULE_LICENSE("GPL v2"); 363