diff options
Diffstat (limited to 'drivers/staging/greybus/arche-apb-ctrl.c')
| -rw-r--r-- | drivers/staging/greybus/arche-apb-ctrl.c | 491 |
1 files changed, 491 insertions, 0 deletions
diff --git a/drivers/staging/greybus/arche-apb-ctrl.c b/drivers/staging/greybus/arche-apb-ctrl.c new file mode 100644 index 000000000..45afa208d --- /dev/null +++ b/drivers/staging/greybus/arche-apb-ctrl.c @@ -0,0 +1,491 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Arche Platform driver to control APB. + * + * Copyright 2014-2015 Google Inc. + * Copyright 2014-2015 Linaro Ltd. + */ + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/gpio/consumer.h> +#include <linux/interrupt.h> +#include <linux/of_irq.h> +#include <linux/module.h> +#include <linux/pinctrl/consumer.h> +#include <linux/platform_device.h> +#include <linux/pm.h> +#include <linux/regulator/consumer.h> +#include <linux/spinlock.h> +#include "arche_platform.h" + +static void apb_bootret_deassert(struct device *dev); + +struct arche_apb_ctrl_drvdata { + /* Control GPIO signals to and from AP <=> AP Bridges */ + struct gpio_desc *resetn; + struct gpio_desc *boot_ret; + struct gpio_desc *pwroff; + struct gpio_desc *wake_in; + struct gpio_desc *wake_out; + struct gpio_desc *pwrdn; + + enum arche_platform_state state; + bool init_disabled; + + struct regulator *vcore; + struct regulator *vio; + + struct gpio_desc *clk_en; + struct clk *clk; + + struct pinctrl *pinctrl; + struct pinctrl_state *pin_default; + + /* V2: SPI Bus control */ + struct gpio_desc *spi_en; + bool spi_en_polarity_high; +}; + +/* + * Note that these low level api's are active high + */ +static inline void deassert_reset(struct gpio_desc *gpio) +{ + gpiod_set_raw_value(gpio, 1); +} + +static inline void assert_reset(struct gpio_desc *gpio) +{ + gpiod_set_raw_value(gpio, 0); +} + +/* + * Note: Please do not modify the below sequence, as it is as per the spec + */ +static int coldboot_seq(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev); + int ret; + + if (apb->init_disabled || + apb->state == ARCHE_PLATFORM_STATE_ACTIVE) + return 0; + + /* Hold APB in reset state */ + assert_reset(apb->resetn); + + if (apb->state == ARCHE_PLATFORM_STATE_FW_FLASHING && apb->spi_en) + devm_gpiod_put(dev, apb->spi_en); + + /* Enable power to APB */ + if (!IS_ERR(apb->vcore)) { + ret = regulator_enable(apb->vcore); + if (ret) { + dev_err(dev, "failed to enable core regulator\n"); + return ret; + } + } + + if (!IS_ERR(apb->vio)) { + ret = regulator_enable(apb->vio); + if (ret) { + dev_err(dev, "failed to enable IO regulator\n"); + return ret; + } + } + + apb_bootret_deassert(dev); + + /* On DB3 clock was not mandatory */ + if (apb->clk_en) + gpiod_set_value(apb->clk_en, 1); + + usleep_range(100, 200); + + /* deassert reset to APB : Active-low signal */ + deassert_reset(apb->resetn); + + apb->state = ARCHE_PLATFORM_STATE_ACTIVE; + + return 0; +} + +static int fw_flashing_seq(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev); + int ret; + + if (apb->init_disabled || + apb->state == ARCHE_PLATFORM_STATE_FW_FLASHING) + return 0; + + ret = regulator_enable(apb->vcore); + if (ret) { + dev_err(dev, "failed to enable core regulator\n"); + return ret; + } + + ret = regulator_enable(apb->vio); + if (ret) { + dev_err(dev, "failed to enable IO regulator\n"); + return ret; + } + + if (apb->spi_en) { + unsigned long flags; + + if (apb->spi_en_polarity_high) + flags = GPIOD_OUT_HIGH; + else + flags = GPIOD_OUT_LOW; + + apb->spi_en = devm_gpiod_get(dev, "spi-en", flags); + if (IS_ERR(apb->spi_en)) { + ret = PTR_ERR(apb->spi_en); + dev_err(dev, "Failed requesting SPI bus en GPIO: %d\n", + ret); + return ret; + } + } + + /* for flashing device should be in reset state */ + assert_reset(apb->resetn); + apb->state = ARCHE_PLATFORM_STATE_FW_FLASHING; + + return 0; +} + +static int standby_boot_seq(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev); + + if (apb->init_disabled) + return 0; + + /* + * Even if it is in OFF state, + * then we do not want to change the state + */ + if (apb->state == ARCHE_PLATFORM_STATE_STANDBY || + apb->state == ARCHE_PLATFORM_STATE_OFF) + return 0; + + if (apb->state == ARCHE_PLATFORM_STATE_FW_FLASHING && apb->spi_en) + devm_gpiod_put(dev, apb->spi_en); + + /* + * As per WDM spec, do nothing + * + * Pasted from WDM spec, + * - A falling edge on POWEROFF_L is detected (a) + * - WDM enters standby mode, but no output signals are changed + */ + + /* TODO: POWEROFF_L is input to WDM module */ + apb->state = ARCHE_PLATFORM_STATE_STANDBY; + return 0; +} + +static void poweroff_seq(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev); + + if (apb->init_disabled || apb->state == ARCHE_PLATFORM_STATE_OFF) + return; + + if (apb->state == ARCHE_PLATFORM_STATE_FW_FLASHING && apb->spi_en) + devm_gpiod_put(dev, apb->spi_en); + + /* disable the clock */ + if (apb->clk_en) + gpiod_set_value(apb->clk_en, 0); + + if (!IS_ERR(apb->vcore) && regulator_is_enabled(apb->vcore) > 0) + regulator_disable(apb->vcore); + + if (!IS_ERR(apb->vio) && regulator_is_enabled(apb->vio) > 0) + regulator_disable(apb->vio); + + /* As part of exit, put APB back in reset state */ + assert_reset(apb->resetn); + apb->state = ARCHE_PLATFORM_STATE_OFF; + + /* TODO: May have to send an event to SVC about this exit */ +} + +static void apb_bootret_deassert(struct device *dev) +{ + struct arche_apb_ctrl_drvdata *apb = dev_get_drvdata(dev); + + gpiod_set_value(apb->boot_ret, 0); +} + +int apb_ctrl_coldboot(struct device *dev) +{ + return coldboot_seq(to_platform_device(dev)); +} + +int apb_ctrl_fw_flashing(struct device *dev) +{ + return fw_flashing_seq(to_platform_device(dev)); +} + +int apb_ctrl_standby_boot(struct device *dev) +{ + return standby_boot_seq(to_platform_device(dev)); +} + +void apb_ctrl_poweroff(struct device *dev) +{ + poweroff_seq(to_platform_device(dev)); +} + +static ssize_t state_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct platform_device *pdev = to_platform_device(dev); + struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev); + int ret = 0; + bool is_disabled; + + if (sysfs_streq(buf, "off")) { + if (apb->state == ARCHE_PLATFORM_STATE_OFF) + return count; + + poweroff_seq(pdev); + } else if (sysfs_streq(buf, "active")) { + if (apb->state == ARCHE_PLATFORM_STATE_ACTIVE) + return count; + + poweroff_seq(pdev); + is_disabled = apb->init_disabled; + apb->init_disabled = false; + ret = coldboot_seq(pdev); + if (ret) + apb->init_disabled = is_disabled; + } else if (sysfs_streq(buf, "standby")) { + if (apb->state == ARCHE_PLATFORM_STATE_STANDBY) + return count; + + ret = standby_boot_seq(pdev); + } else if (sysfs_streq(buf, "fw_flashing")) { + if (apb->state == ARCHE_PLATFORM_STATE_FW_FLASHING) + return count; + + /* + * First we want to make sure we power off everything + * and then enter FW flashing state + */ + poweroff_seq(pdev); + ret = fw_flashing_seq(pdev); + } else { + dev_err(dev, "unknown state\n"); + ret = -EINVAL; + } + + return ret ? ret : count; +} + +static ssize_t state_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct arche_apb_ctrl_drvdata *apb = dev_get_drvdata(dev); + + switch (apb->state) { + case ARCHE_PLATFORM_STATE_OFF: + return sprintf(buf, "off%s\n", + apb->init_disabled ? ",disabled" : ""); + case ARCHE_PLATFORM_STATE_ACTIVE: + return sprintf(buf, "active\n"); + case ARCHE_PLATFORM_STATE_STANDBY: + return sprintf(buf, "standby\n"); + case ARCHE_PLATFORM_STATE_FW_FLASHING: + return sprintf(buf, "fw_flashing\n"); + default: + return sprintf(buf, "unknown state\n"); + } +} + +static DEVICE_ATTR_RW(state); + +static int apb_ctrl_get_devtree_data(struct platform_device *pdev, + struct arche_apb_ctrl_drvdata *apb) +{ + struct device *dev = &pdev->dev; + int ret; + + apb->resetn = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW); + if (IS_ERR(apb->resetn)) { + ret = PTR_ERR(apb->resetn); + dev_err(dev, "Failed requesting reset GPIO: %d\n", ret); + return ret; + } + + apb->boot_ret = devm_gpiod_get(dev, "boot-ret", GPIOD_OUT_LOW); + if (IS_ERR(apb->boot_ret)) { + ret = PTR_ERR(apb->boot_ret); + dev_err(dev, "Failed requesting bootret GPIO: %d\n", ret); + return ret; + } + + /* It's not mandatory to support power management interface */ + apb->pwroff = devm_gpiod_get_optional(dev, "pwr-off", GPIOD_IN); + if (IS_ERR(apb->pwroff)) { + ret = PTR_ERR(apb->pwroff); + dev_err(dev, "Failed requesting pwroff_n GPIO: %d\n", ret); + return ret; + } + + /* Do not make clock mandatory as of now (for DB3) */ + apb->clk_en = devm_gpiod_get_optional(dev, "clock-en", GPIOD_OUT_LOW); + if (IS_ERR(apb->clk_en)) { + ret = PTR_ERR(apb->clk_en); + dev_err(dev, "Failed requesting APB clock en GPIO: %d\n", ret); + return ret; + } + + apb->pwrdn = devm_gpiod_get(dev, "pwr-down", GPIOD_OUT_LOW); + if (IS_ERR(apb->pwrdn)) { + ret = PTR_ERR(apb->pwrdn); + dev_warn(dev, "Failed requesting power down GPIO: %d\n", ret); + return ret; + } + + /* Regulators are optional, as we may have fixed supply coming in */ + apb->vcore = devm_regulator_get(dev, "vcore"); + if (IS_ERR(apb->vcore)) + dev_warn(dev, "no core regulator found\n"); + + apb->vio = devm_regulator_get(dev, "vio"); + if (IS_ERR(apb->vio)) + dev_warn(dev, "no IO regulator found\n"); + + apb->pinctrl = devm_pinctrl_get(&pdev->dev); + if (IS_ERR(apb->pinctrl)) { + dev_err(&pdev->dev, "could not get pinctrl handle\n"); + return PTR_ERR(apb->pinctrl); + } + apb->pin_default = pinctrl_lookup_state(apb->pinctrl, "default"); + if (IS_ERR(apb->pin_default)) { + dev_err(&pdev->dev, "could not get default pin state\n"); + return PTR_ERR(apb->pin_default); + } + + /* Only applicable for platform >= V2 */ + if (of_property_read_bool(pdev->dev.of_node, "gb,spi-en-active-high")) + apb->spi_en_polarity_high = true; + + return 0; +} + +static int arche_apb_ctrl_probe(struct platform_device *pdev) +{ + int ret; + struct arche_apb_ctrl_drvdata *apb; + struct device *dev = &pdev->dev; + + apb = devm_kzalloc(&pdev->dev, sizeof(*apb), GFP_KERNEL); + if (!apb) + return -ENOMEM; + + ret = apb_ctrl_get_devtree_data(pdev, apb); + if (ret) { + dev_err(dev, "failed to get apb devicetree data %d\n", ret); + return ret; + } + + /* Initially set APB to OFF state */ + apb->state = ARCHE_PLATFORM_STATE_OFF; + /* Check whether device needs to be enabled on boot */ + if (of_property_read_bool(pdev->dev.of_node, "arche,init-disable")) + apb->init_disabled = true; + + platform_set_drvdata(pdev, apb); + + /* Create sysfs interface to allow user to change state dynamically */ + ret = device_create_file(dev, &dev_attr_state); + if (ret) { + dev_err(dev, "failed to create state file in sysfs\n"); + return ret; + } + + dev_info(&pdev->dev, "Device registered successfully\n"); + return 0; +} + +static int arche_apb_ctrl_remove(struct platform_device *pdev) +{ + device_remove_file(&pdev->dev, &dev_attr_state); + poweroff_seq(pdev); + platform_set_drvdata(pdev, NULL); + + return 0; +} + +static int __maybe_unused arche_apb_ctrl_suspend(struct device *dev) +{ + /* + * If timing profile permits, we may shutdown bridge + * completely + * + * TODO: sequence ?? + * + * Also, need to make sure we meet precondition for unipro suspend + * Precondition: Definition ??? + */ + return 0; +} + +static int __maybe_unused arche_apb_ctrl_resume(struct device *dev) +{ + /* + * At least for ES2 we have to meet the delay requirement between + * unipro switch and AP bridge init, depending on whether bridge is in + * OFF state or standby state. + * + * Based on whether bridge is in standby or OFF state we may have to + * assert multiple signals. Please refer to WDM spec, for more info. + * + */ + return 0; +} + +static void arche_apb_ctrl_shutdown(struct platform_device *pdev) +{ + apb_ctrl_poweroff(&pdev->dev); +} + +static SIMPLE_DEV_PM_OPS(arche_apb_ctrl_pm_ops, arche_apb_ctrl_suspend, + arche_apb_ctrl_resume); + +static const struct of_device_id arche_apb_ctrl_of_match[] = { + { .compatible = "usbffff,2", }, + { }, +}; + +static struct platform_driver arche_apb_ctrl_device_driver = { + .probe = arche_apb_ctrl_probe, + .remove = arche_apb_ctrl_remove, + .shutdown = arche_apb_ctrl_shutdown, + .driver = { + .name = "arche-apb-ctrl", + .pm = &arche_apb_ctrl_pm_ops, + .of_match_table = arche_apb_ctrl_of_match, + } +}; + +int __init arche_apb_init(void) +{ + return platform_driver_register(&arche_apb_ctrl_device_driver); +} + +void __exit arche_apb_exit(void) +{ + platform_driver_unregister(&arche_apb_ctrl_device_driver); +} |