317 lines
7.4 KiB
C
317 lines
7.4 KiB
C
/*
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* Arche Platform driver to control APB.
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*
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* Copyright 2014-2015 Google Inc.
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* Copyright 2014-2015 Linaro Ltd.
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*
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* Released under the GPLv2 only.
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*/
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#include <linux/clk.h>
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#include <linux/delay.h>
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#include <linux/gpio.h>
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#include <linux/interrupt.h>
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#include <linux/of_gpio.h>
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#include <linux/of_irq.h>
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#include <linux/module.h>
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#include <linux/pinctrl/consumer.h>
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#include <linux/platform_device.h>
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#include <linux/pm.h>
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#include <linux/regulator/consumer.h>
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#include <linux/spinlock.h>
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#include "arche_platform.h"
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enum apb_state {
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APB_STATE_OFF,
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APB_STATE_ACTIVE,
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APB_STATE_STANDBY,
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};
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struct arche_apb_ctrl_drvdata {
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/* Control GPIO signals to and from AP <=> AP Bridges */
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int resetn_gpio;
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int boot_ret_gpio;
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int pwroff_gpio;
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int wake_in_gpio;
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int wake_out_gpio;
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int pwrdn_gpio;
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enum apb_state state;
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struct regulator *vcore;
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struct regulator *vio;
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unsigned int clk_en_gpio;
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struct clk *clk;
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struct pinctrl *pinctrl;
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struct pinctrl_state *pin_default;
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};
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/*
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* Note that these low level api's are active high
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*/
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static inline void deassert_reset(unsigned int gpio)
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{
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gpio_set_value(gpio, 1);
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msleep(500);
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}
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static inline void assert_reset(unsigned int gpio)
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{
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gpio_set_value(gpio, 0);
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}
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/* Export gpio's to user space */
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static void export_gpios(struct arche_apb_ctrl_drvdata *apb)
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{
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gpio_export(apb->resetn_gpio, false);
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}
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static void unexport_gpios(struct arche_apb_ctrl_drvdata *apb)
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{
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gpio_unexport(apb->resetn_gpio);
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}
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/*
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* Note: Please do not modify the below sequence, as it is as per the spec
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*/
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static int apb_ctrl_init_seq(struct platform_device *pdev,
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struct arche_apb_ctrl_drvdata *apb)
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{
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struct device *dev = &pdev->dev;
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int ret;
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/* Hold APB in reset state */
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ret = devm_gpio_request(dev, apb->resetn_gpio, "apb-reset");
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if (ret) {
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dev_err(dev, "Failed requesting reset gpio %d\n",
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apb->resetn_gpio);
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return ret;
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}
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ret = gpio_direction_output(apb->resetn_gpio, 0);
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if (ret) {
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dev_err(dev, "failed to set reset gpio dir:%d\n", ret);
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return ret;
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}
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ret = devm_gpio_request(dev, apb->pwroff_gpio, "pwroff_n");
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if (ret) {
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dev_err(dev, "Failed requesting pwroff_n gpio %d\n",
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apb->pwroff_gpio);
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return ret;
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}
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ret = gpio_direction_input(apb->pwroff_gpio);
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if (ret) {
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dev_err(dev, "failed to set pwroff gpio dir:%d\n", ret);
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return ret;
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}
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/* Enable power to APB */
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if (!IS_ERR(apb->vcore)) {
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ret = regulator_enable(apb->vcore);
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if (ret) {
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dev_err(dev, "failed to enable core regulator\n");
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return ret;
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}
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}
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if (!IS_ERR(apb->vio)) {
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ret = regulator_enable(apb->vio);
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if (ret) {
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dev_err(dev, "failed to enable IO regulator\n");
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goto out_vcore_disable;
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}
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}
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ret = devm_gpio_request_one(dev, apb->boot_ret_gpio,
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GPIOF_OUT_INIT_LOW, "boot retention");
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if (ret) {
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dev_err(dev, "Failed requesting bootret gpio %d\n",
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apb->boot_ret_gpio);
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goto out_vio_disable;
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}
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gpio_set_value(apb->boot_ret_gpio, 0);
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/* On DB3 clock was not mandatory */
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if (gpio_is_valid(apb->clk_en_gpio)) {
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ret = devm_gpio_request(dev, apb->clk_en_gpio, "apb_clk_en");
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if (ret) {
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dev_warn(dev, "Failed requesting APB clock en gpio %d\n",
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apb->clk_en_gpio);
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} else {
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ret = gpio_direction_output(apb->clk_en_gpio, 1);
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if (ret)
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dev_warn(dev, "failed to set APB clock en gpio dir:%d\n",
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ret);
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}
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}
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usleep_range(100, 200);
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return 0;
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out_vio_disable:
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if (!IS_ERR(apb->vio))
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regulator_disable(apb->vio);
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out_vcore_disable:
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if (!IS_ERR(apb->vcore))
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regulator_disable(apb->vcore);
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return ret;
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}
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static int apb_ctrl_get_devtree_data(struct platform_device *pdev,
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struct arche_apb_ctrl_drvdata *apb)
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{
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struct device *dev = &pdev->dev;
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struct device_node *np = dev->of_node;
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apb->resetn_gpio = of_get_named_gpio(np, "reset-gpios", 0);
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if (apb->resetn_gpio < 0) {
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dev_err(dev, "failed to get reset gpio\n");
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return apb->resetn_gpio;
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}
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apb->boot_ret_gpio = of_get_named_gpio(np, "boot-ret-gpios", 0);
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if (apb->boot_ret_gpio < 0) {
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dev_err(dev, "failed to get boot retention gpio\n");
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return apb->boot_ret_gpio;
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}
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/* It's not mandatory to support power management interface */
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apb->pwroff_gpio = of_get_named_gpio(np, "pwr-off-gpios", 0);
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if (apb->pwroff_gpio < 0) {
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dev_err(dev, "failed to get power off gpio\n");
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return apb->pwroff_gpio;
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}
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/* Do not make clock mandatory as of now (for DB3) */
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apb->clk_en_gpio = of_get_named_gpio(np, "clock-en-gpio", 0);
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if (apb->clk_en_gpio < 0)
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dev_warn(dev, "failed to get clock en gpio\n");
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apb->pwrdn_gpio = of_get_named_gpio(np, "pwr-down-gpios", 0);
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if (apb->pwrdn_gpio < 0)
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dev_warn(dev, "failed to get power down gpio\n");
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/* Regulators are optional, as we may have fixed supply coming in */
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apb->vcore = devm_regulator_get(dev, "vcore");
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if (IS_ERR(apb->vcore))
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dev_warn(dev, "no core regulator found\n");
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apb->vio = devm_regulator_get(dev, "vio");
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if (IS_ERR(apb->vio))
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dev_warn(dev, "no IO regulator found\n");
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apb->pinctrl = devm_pinctrl_get(&pdev->dev);
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if (IS_ERR(apb->pinctrl)) {
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dev_err(&pdev->dev, "could not get pinctrl handle\n");
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return PTR_ERR(apb->pinctrl);
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}
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apb->pin_default = pinctrl_lookup_state(apb->pinctrl, "default");
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if (IS_ERR(apb->pin_default)) {
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dev_err(&pdev->dev, "could not get default pin state\n");
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return PTR_ERR(apb->pin_default);
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}
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return 0;
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}
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static void apb_ctrl_cleanup(struct arche_apb_ctrl_drvdata *apb)
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{
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/* disable the clock */
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if (gpio_is_valid(apb->clk_en_gpio))
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gpio_set_value(apb->clk_en_gpio, 0);
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if (!IS_ERR(apb->vcore) && regulator_is_enabled(apb->vcore) > 0)
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regulator_disable(apb->vcore);
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if (!IS_ERR(apb->vio) && regulator_is_enabled(apb->vio) > 0)
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regulator_disable(apb->vio);
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/* As part of exit, put APB back in reset state */
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assert_reset(apb->resetn_gpio);
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apb->state = APB_STATE_OFF;
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/* TODO: May have to send an event to SVC about this exit */
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}
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int arche_apb_ctrl_probe(struct platform_device *pdev)
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{
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int ret;
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struct arche_apb_ctrl_drvdata *apb;
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struct device *dev = &pdev->dev;
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apb = devm_kzalloc(&pdev->dev, sizeof(*apb), GFP_KERNEL);
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if (!apb)
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return -ENOMEM;
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ret = apb_ctrl_get_devtree_data(pdev, apb);
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if (ret) {
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dev_err(dev, "failed to get apb devicetree data %d\n", ret);
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return ret;
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}
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ret = apb_ctrl_init_seq(pdev, apb);
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if (ret) {
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dev_err(dev, "failed to set init state of control signal %d\n",
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ret);
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return ret;
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}
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/* deassert reset to APB : Active-low signal */
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deassert_reset(apb->resetn_gpio);
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apb->state = APB_STATE_ACTIVE;
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platform_set_drvdata(pdev, apb);
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export_gpios(apb);
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dev_info(&pdev->dev, "Device registered successfully\n");
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return 0;
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}
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int arche_apb_ctrl_remove(struct platform_device *pdev)
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{
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struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev);
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apb_ctrl_cleanup(apb);
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platform_set_drvdata(pdev, NULL);
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unexport_gpios(apb);
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return 0;
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}
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static int arche_apb_ctrl_suspend(struct device *dev)
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{
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/*
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* If timing profile permits, we may shutdown bridge
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* completely
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*
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* TODO: sequence ??
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*
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* Also, need to make sure we meet precondition for unipro suspend
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* Precondition: Definition ???
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*/
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return 0;
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}
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static int arche_apb_ctrl_resume(struct device *dev)
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{
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/*
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* Atleast for ES2 we have to meet the delay requirement between
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* unipro switch and AP bridge init, depending on whether bridge is in
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* OFF state or standby state.
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*
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* Based on whether bridge is in standby or OFF state we may have to
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* assert multiple signals. Please refer to WDM spec, for more info.
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*
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*/
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return 0;
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}
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SIMPLE_DEV_PM_OPS(arche_apb_ctrl_pm_ops,
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arche_apb_ctrl_suspend,
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arche_apb_ctrl_resume);
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