// SPDX-License-Identifier: GPL-2.0 /* * Expose a PWM controlled by the ChromeOS EC to the host processor. * * Copyright (C) 2016 Google, Inc. */ #include #include #include #include #include #include #include #include /** * struct cros_ec_pwm_device - Driver data for EC PWM * * @ec: Pointer to EC device * @use_pwm_type: Use PWM types instead of generic channels * @channel: array with per-channel data */ struct cros_ec_pwm_device { struct cros_ec_device *ec; bool use_pwm_type; struct cros_ec_pwm *channel; }; /** * struct cros_ec_pwm - per-PWM driver data * @duty_cycle: cached duty cycle */ struct cros_ec_pwm { u16 duty_cycle; }; static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *chip) { return pwmchip_get_drvdata(chip); } static int cros_ec_dt_type_to_pwm_type(u8 dt_index, u8 *pwm_type) { switch (dt_index) { case CROS_EC_PWM_DT_KB_LIGHT: *pwm_type = EC_PWM_TYPE_KB_LIGHT; return 0; case CROS_EC_PWM_DT_DISPLAY_LIGHT: *pwm_type = EC_PWM_TYPE_DISPLAY_LIGHT; return 0; default: return -EINVAL; } } static int cros_ec_pwm_set_duty(struct cros_ec_pwm_device *ec_pwm, u8 index, u16 duty) { struct cros_ec_device *ec = ec_pwm->ec; struct { struct cros_ec_command msg; struct ec_params_pwm_set_duty params; } __packed buf; struct ec_params_pwm_set_duty *params = &buf.params; struct cros_ec_command *msg = &buf.msg; int ret; memset(&buf, 0, sizeof(buf)); msg->version = 0; msg->command = EC_CMD_PWM_SET_DUTY; msg->insize = 0; msg->outsize = sizeof(*params); params->duty = duty; if (ec_pwm->use_pwm_type) { ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type); if (ret) { dev_err(ec->dev, "Invalid PWM type index: %d\n", index); return ret; } params->index = 0; } else { params->pwm_type = EC_PWM_TYPE_GENERIC; params->index = index; } return cros_ec_cmd_xfer_status(ec, msg); } static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, bool use_pwm_type, u8 index) { struct { struct cros_ec_command msg; union { struct ec_params_pwm_get_duty params; struct ec_response_pwm_get_duty resp; }; } __packed buf; struct ec_params_pwm_get_duty *params = &buf.params; struct ec_response_pwm_get_duty *resp = &buf.resp; struct cros_ec_command *msg = &buf.msg; int ret; memset(&buf, 0, sizeof(buf)); msg->version = 0; msg->command = EC_CMD_PWM_GET_DUTY; msg->insize = sizeof(*resp); msg->outsize = sizeof(*params); if (use_pwm_type) { ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type); if (ret) { dev_err(ec->dev, "Invalid PWM type index: %d\n", index); return ret; } params->index = 0; } else { params->pwm_type = EC_PWM_TYPE_GENERIC; params->index = index; } ret = cros_ec_cmd_xfer_status(ec, msg); if (ret < 0) return ret; return resp->duty; } static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_state *state) { struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); struct cros_ec_pwm *channel = &ec_pwm->channel[pwm->hwpwm]; u16 duty_cycle; int ret; /* The EC won't let us change the period */ if (state->period != EC_PWM_MAX_DUTY) return -EINVAL; if (state->polarity != PWM_POLARITY_NORMAL) return -EINVAL; /* * EC doesn't separate the concept of duty cycle and enabled, but * kernel does. Translate. */ duty_cycle = state->enabled ? state->duty_cycle : 0; ret = cros_ec_pwm_set_duty(ec_pwm, pwm->hwpwm, duty_cycle); if (ret < 0) return ret; channel->duty_cycle = state->duty_cycle; return 0; } static int cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state) { struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip); struct cros_ec_pwm *channel = &ec_pwm->channel[pwm->hwpwm]; int ret; ret = cros_ec_pwm_get_duty(ec_pwm->ec, ec_pwm->use_pwm_type, pwm->hwpwm); if (ret < 0) { dev_err(pwmchip_parent(chip), "error getting initial duty: %d\n", ret); return ret; } state->enabled = (ret > 0); state->period = EC_PWM_MAX_DUTY; state->polarity = PWM_POLARITY_NORMAL; /* * Note that "disabled" and "duty cycle == 0" are treated the same. If * the cached duty cycle is not zero, used the cached duty cycle. This * ensures that the configured duty cycle is kept across a disable and * enable operation and avoids potentially confusing consumers. * * For the case of the initial hardware readout, channel->duty_cycle * will be 0 and the actual duty cycle read from the EC is used. */ if (ret == 0 && channel->duty_cycle > 0) state->duty_cycle = channel->duty_cycle; else state->duty_cycle = ret; return 0; } static struct pwm_device * cros_ec_pwm_xlate(struct pwm_chip *chip, const struct of_phandle_args *args) { struct pwm_device *pwm; if (args->args[0] >= chip->npwm) return ERR_PTR(-EINVAL); pwm = pwm_request_from_chip(chip, args->args[0], NULL); if (IS_ERR(pwm)) return pwm; /* The EC won't let us change the period */ pwm->args.period = EC_PWM_MAX_DUTY; return pwm; } static const struct pwm_ops cros_ec_pwm_ops = { .get_state = cros_ec_pwm_get_state, .apply = cros_ec_pwm_apply, }; /* * Determine the number of supported PWMs. The EC does not return the number * of PWMs it supports directly, so we have to read the pwm duty cycle for * subsequent channels until we get an error. */ static int cros_ec_num_pwms(struct cros_ec_device *ec) { int i, ret; /* The index field is only 8 bits */ for (i = 0; i <= U8_MAX; i++) { /* * Note that this function is only called when use_pwm_type is * false. With use_pwm_type == true the number of PWMs is fixed. */ ret = cros_ec_pwm_get_duty(ec, false, i); /* * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM * responses; everything else is treated as an error. * The EC error codes map to -EOPNOTSUPP and -EINVAL, * so check for those. */ switch (ret) { case -EOPNOTSUPP: /* invalid command */ return -ENODEV; case -EINVAL: /* invalid parameter */ return i; default: if (ret < 0) return ret; break; } } return U8_MAX; } static int cros_ec_pwm_probe(struct platform_device *pdev) { struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent); struct device *dev = &pdev->dev; struct device_node *np = pdev->dev.of_node; struct cros_ec_pwm_device *ec_pwm; struct pwm_chip *chip; bool use_pwm_type = false; unsigned int npwm; int ret; if (!ec) return dev_err_probe(dev, -EINVAL, "no parent EC device\n"); if (of_device_is_compatible(np, "google,cros-ec-pwm-type")) { use_pwm_type = true; npwm = CROS_EC_PWM_DT_COUNT; } else { ret = cros_ec_num_pwms(ec); if (ret < 0) return dev_err_probe(dev, ret, "Couldn't find PWMs\n"); npwm = ret; } chip = devm_pwmchip_alloc(dev, npwm, sizeof(*ec_pwm)); if (IS_ERR(chip)) return PTR_ERR(chip); ec_pwm = pwm_to_cros_ec_pwm(chip); ec_pwm->use_pwm_type = use_pwm_type; ec_pwm->ec = ec; /* PWM chip */ chip->ops = &cros_ec_pwm_ops; chip->of_xlate = cros_ec_pwm_xlate; ec_pwm->channel = devm_kcalloc(dev, chip->npwm, sizeof(*ec_pwm->channel), GFP_KERNEL); if (!ec_pwm->channel) return -ENOMEM; dev_dbg(dev, "Probed %u PWMs\n", chip->npwm); ret = devm_pwmchip_add(dev, chip); if (ret < 0) return dev_err_probe(dev, ret, "cannot register PWM\n"); return 0; } #ifdef CONFIG_OF static const struct of_device_id cros_ec_pwm_of_match[] = { { .compatible = "google,cros-ec-pwm" }, { .compatible = "google,cros-ec-pwm-type" }, {}, }; MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match); #endif static struct platform_driver cros_ec_pwm_driver = { .probe = cros_ec_pwm_probe, .driver = { .name = "cros-ec-pwm", .of_match_table = of_match_ptr(cros_ec_pwm_of_match), }, }; module_platform_driver(cros_ec_pwm_driver); MODULE_ALIAS("platform:cros-ec-pwm"); MODULE_DESCRIPTION("ChromeOS EC PWM driver"); MODULE_LICENSE("GPL v2");