1 /* 2 * Copyright (C) 2016 Google, Inc 3 * 4 * This program is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2, as published by 6 * the Free Software Foundation. 7 * 8 * Expose a PWM controlled by the ChromeOS EC to the host processor. 9 */ 10 11 #include <linux/module.h> 12 #include <linux/mfd/cros_ec.h> 13 #include <linux/mfd/cros_ec_commands.h> 14 #include <linux/platform_device.h> 15 #include <linux/pwm.h> 16 #include <linux/slab.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 */ 25 struct cros_ec_pwm_device { 26 struct device *dev; 27 struct cros_ec_device *ec; 28 struct pwm_chip chip; 29 }; 30 31 static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *c) 32 { 33 return container_of(c, struct cros_ec_pwm_device, chip); 34 } 35 36 static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty) 37 { 38 struct { 39 struct cros_ec_command msg; 40 struct ec_params_pwm_set_duty params; 41 } __packed buf; 42 struct ec_params_pwm_set_duty *params = &buf.params; 43 struct cros_ec_command *msg = &buf.msg; 44 45 memset(&buf, 0, sizeof(buf)); 46 47 msg->version = 0; 48 msg->command = EC_CMD_PWM_SET_DUTY; 49 msg->insize = 0; 50 msg->outsize = sizeof(*params); 51 52 params->duty = duty; 53 params->pwm_type = EC_PWM_TYPE_GENERIC; 54 params->index = index; 55 56 return cros_ec_cmd_xfer_status(ec, msg); 57 } 58 59 static int __cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index, 60 u32 *result) 61 { 62 struct { 63 struct cros_ec_command msg; 64 union { 65 struct ec_params_pwm_get_duty params; 66 struct ec_response_pwm_get_duty resp; 67 }; 68 } __packed buf; 69 struct ec_params_pwm_get_duty *params = &buf.params; 70 struct ec_response_pwm_get_duty *resp = &buf.resp; 71 struct cros_ec_command *msg = &buf.msg; 72 int ret; 73 74 memset(&buf, 0, sizeof(buf)); 75 76 msg->version = 0; 77 msg->command = EC_CMD_PWM_GET_DUTY; 78 msg->insize = sizeof(*resp); 79 msg->outsize = sizeof(*params); 80 81 params->pwm_type = EC_PWM_TYPE_GENERIC; 82 params->index = index; 83 84 ret = cros_ec_cmd_xfer_status(ec, msg); 85 if (result) 86 *result = msg->result; 87 if (ret < 0) 88 return ret; 89 90 return resp->duty; 91 } 92 93 static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index) 94 { 95 return __cros_ec_pwm_get_duty(ec, index, NULL); 96 } 97 98 static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, 99 struct pwm_state *state) 100 { 101 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 102 int duty_cycle; 103 104 /* The EC won't let us change the period */ 105 if (state->period != EC_PWM_MAX_DUTY) 106 return -EINVAL; 107 108 /* 109 * EC doesn't separate the concept of duty cycle and enabled, but 110 * kernel does. Translate. 111 */ 112 duty_cycle = state->enabled ? state->duty_cycle : 0; 113 114 return cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle); 115 } 116 117 static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, 118 struct pwm_state *state) 119 { 120 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); 121 int ret; 122 123 ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm); 124 if (ret < 0) { 125 dev_err(chip->dev, "error getting initial duty: %d\n", ret); 126 return; 127 } 128 129 state->enabled = (ret > 0); 130 state->period = EC_PWM_MAX_DUTY; 131 132 /* Note that "disabled" and "duty cycle == 0" are treated the same */ 133 state->duty_cycle = ret; 134 } 135 136 static struct pwm_device * 137 cros_ec_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args) 138 { 139 struct pwm_device *pwm; 140 141 if (args->args[0] >= pc->npwm) 142 return ERR_PTR(-EINVAL); 143 144 pwm = pwm_request_from_chip(pc, args->args[0], NULL); 145 if (IS_ERR(pwm)) 146 return pwm; 147 148 /* The EC won't let us change the period */ 149 pwm->args.period = EC_PWM_MAX_DUTY; 150 151 return pwm; 152 } 153 154 static const struct pwm_ops cros_ec_pwm_ops = { 155 .get_state = cros_ec_pwm_get_state, 156 .apply = cros_ec_pwm_apply, 157 .owner = THIS_MODULE, 158 }; 159 160 static int cros_ec_num_pwms(struct cros_ec_device *ec) 161 { 162 int i, ret; 163 164 /* The index field is only 8 bits */ 165 for (i = 0; i <= U8_MAX; i++) { 166 u32 result = 0; 167 168 ret = __cros_ec_pwm_get_duty(ec, i, &result); 169 /* We want to parse EC protocol errors */ 170 if (ret < 0 && !(ret == -EPROTO && result)) 171 return ret; 172 173 /* 174 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM 175 * responses; everything else is treated as an error. 176 */ 177 if (result == EC_RES_INVALID_COMMAND) 178 return -ENODEV; 179 else if (result == EC_RES_INVALID_PARAM) 180 return i; 181 else if (result) 182 return -EPROTO; 183 } 184 185 return U8_MAX; 186 } 187 188 static int cros_ec_pwm_probe(struct platform_device *pdev) 189 { 190 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); 191 struct device *dev = &pdev->dev; 192 struct cros_ec_pwm_device *ec_pwm; 193 struct pwm_chip *chip; 194 int ret; 195 196 if (!ec) { 197 dev_err(dev, "no parent EC device\n"); 198 return -EINVAL; 199 } 200 201 ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL); 202 if (!ec_pwm) 203 return -ENOMEM; 204 chip = &ec_pwm->chip; 205 ec_pwm->ec = ec; 206 207 /* PWM chip */ 208 chip->dev = dev; 209 chip->ops = &cros_ec_pwm_ops; 210 chip->of_xlate = cros_ec_pwm_xlate; 211 chip->of_pwm_n_cells = 1; 212 chip->base = -1; 213 ret = cros_ec_num_pwms(ec); 214 if (ret < 0) { 215 dev_err(dev, "Couldn't find PWMs: %d\n", ret); 216 return ret; 217 } 218 chip->npwm = ret; 219 dev_dbg(dev, "Probed %u PWMs\n", chip->npwm); 220 221 ret = pwmchip_add(chip); 222 if (ret < 0) { 223 dev_err(dev, "cannot register PWM: %d\n", ret); 224 return ret; 225 } 226 227 platform_set_drvdata(pdev, ec_pwm); 228 229 return ret; 230 } 231 232 static int cros_ec_pwm_remove(struct platform_device *dev) 233 { 234 struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev); 235 struct pwm_chip *chip = &ec_pwm->chip; 236 237 return pwmchip_remove(chip); 238 } 239 240 #ifdef CONFIG_OF 241 static const struct of_device_id cros_ec_pwm_of_match[] = { 242 { .compatible = "google,cros-ec-pwm" }, 243 {}, 244 }; 245 MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match); 246 #endif 247 248 static struct platform_driver cros_ec_pwm_driver = { 249 .probe = cros_ec_pwm_probe, 250 .remove = cros_ec_pwm_remove, 251 .driver = { 252 .name = "cros-ec-pwm", 253 .of_match_table = of_match_ptr(cros_ec_pwm_of_match), 254 }, 255 }; 256 module_platform_driver(cros_ec_pwm_driver); 257 258 MODULE_ALIAS("platform:cros-ec-pwm"); 259 MODULE_DESCRIPTION("ChromeOS EC PWM driver"); 260 MODULE_LICENSE("GPL v2"); 261