--- /dev/null
+/*
+ * DB3 Platform driver for AP bridge control interface.
+ *
+ * Copyright 2014-2015 Google Inc.
+ * Copyright 2014-2015 Linaro Ltd.
+ *
+ * Released under the GPLv2 only.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/sched.h>
+#include <linux/pm.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+#include <linux/of_platform.h>
+#include <linux/of_gpio.h>
+#include <linux/of_irq.h>
+#include <linux/spinlock.h>
+#include <linux/regulator/consumer.h>
+#include <linux/pinctrl/consumer.h>
+
+enum apb_state {
+ APB_STATE_OFF,
+ APB_STATE_ACTIVE,
+ APB_STATE_STANDBY,
+};
+
+/*
+ * Control GPIO signals to and from AP <=> AP Bridges
+ */
+struct apb_ctrl_gpios {
+ int wake_detect; /* bi-dir, maps to WAKE_MOD and WAKE_FRAME signals */
+ int reset;
+ int boot_ret;
+ int pwroff;
+ int wake_in;
+ int wake_out;
+ int pwrdn;
+};
+
+struct apb_ctrl_drvdata {
+ struct apb_ctrl_gpios ctrl;
+
+ unsigned int wake_detect_irq;
+ enum apb_state state;
+
+ struct regulator *vcore;
+ struct regulator *vio;
+
+ struct pinctrl *pinctrl;
+ struct pinctrl_state *pin_default;
+
+ /* To protect concurrent access of GPIO registers, need protection */
+ spinlock_t lock;
+};
+
+static inline void assert_wake(unsigned int wake_detect)
+{
+ gpio_set_value(wake_detect, 1);
+}
+
+static inline void deassert_wake(unsigned int wake_detect)
+{
+ gpio_set_value(wake_detect, 0);
+}
+
+static irqreturn_t apb_ctrl_wake_detect_irq(int irq, void *devid)
+{
+ struct apb_ctrl_drvdata *apb_data = devid;
+ unsigned long flags;
+
+ /*
+ * TODO:
+ * Since currently SoC gpio's are being used we are safe here
+ * But ideally we should create a workqueue and process the control
+ * signals, especially when we start using GPIO's over slow
+ * buses like I2C.
+ */
+ if (!gpio_is_valid(apb_data->ctrl.wake_detect) &&
+ !gpio_is_valid(apb_data->ctrl.reset))
+ return IRQ_HANDLED; /* Should it be IRQ_NONE ?? */
+
+ spin_lock_irqsave(&apb_data->lock, flags);
+
+ if (apb_data->state != APB_STATE_ACTIVE) {
+ /* Bring bridge out of reset on this event */
+ gpio_set_value(apb_data->ctrl.reset, 0);
+ apb_data->state = APB_STATE_ACTIVE;
+ } else {
+ /*
+ * Assert Wake_OUT signal to APB
+ * It would resemble WakeDetect module's signal pass-through
+ */
+ /*
+ * We have to generate the pulse, so we may need to schedule
+ * workqueue here.
+ *
+ * Also, since we are using both rising and falling edge for
+ * interrupt trigger, we may not need workqueue. Just pass
+ * through the value to bridge.
+ * Just read GPIO value and pass it to the bridge
+ */
+ }
+
+ spin_unlock_irqrestore(&apb_data->lock, flags);
+
+ return IRQ_HANDLED;
+}
+
+static void apb_ctrl_cleanup(struct apb_ctrl_drvdata *apb_data)
+{
+ if (apb_data->vcore && regulator_is_enabled(apb_data->vcore) > 0)
+ regulator_disable(apb_data->vcore);
+
+ if (apb_data->vio && regulator_is_enabled(apb_data->vio) > 0)
+ regulator_disable(apb_data->vio);
+
+ /* As part of exit, put APB back in reset state */
+ if (gpio_is_valid(apb_data->ctrl.reset))
+ gpio_set_value(apb_data->ctrl.reset, 1);
+
+ /* TODO: May have to send an event to SVC about this exit */
+}
+
+/*
+ * Note: Please do not modify the below sequence, as it is as per the spec
+ */
+static int apb_ctrl_init_seq(struct device *dev,
+ struct apb_ctrl_drvdata *apb_data)
+{
+ int ret;
+
+ pinctrl_select_state(apb_data->pinctrl, apb_data->pin_default);
+
+ /* Hold APB in reset state */
+ ret = devm_gpio_request_one(dev, apb_data->ctrl.reset,
+ GPIOF_OUT_INIT_LOW, "reset");
+ if (ret) {
+ dev_err(dev, "Failed requesting reset gpio %d\n",
+ apb_data->ctrl.reset);
+ return ret;
+ }
+
+ /* Enable power to APB */
+ if (apb_data->vcore) {
+ ret = regulator_enable(apb_data->vcore);
+ if (ret) {
+ dev_err(dev, "failed to enable core regulator\n");
+ return ret;
+ }
+ }
+
+ if (apb_data->vio) {
+ ret = regulator_enable(apb_data->vio);
+ if (ret) {
+ dev_err(dev, "failed to enable IO regulator\n");
+ return ret;
+ }
+ }
+
+ /*
+ * We should be safe here to deassert boot retention signal, as
+ * we are only supporting cold boot as of now.
+ */
+ ret = devm_gpio_request_one(dev, apb_data->ctrl.boot_ret,
+ GPIOF_OUT_INIT_LOW, "boot retention");
+ if (ret) {
+ dev_err(dev, "Failed requesting reset gpio %d\n",
+ apb_data->ctrl.boot_ret);
+ return ret;
+ }
+
+ ret = devm_gpio_request(dev, apb_data->ctrl.wake_detect, "wake detect");
+ if (ret)
+ dev_err(dev, "Failed requesting wake_detect gpio %d\n",
+ apb_data->ctrl.wake_detect);
+
+ return ret;
+}
+
+static int apb_ctrl_get_devtree_data(struct device *dev,
+ struct apb_ctrl_drvdata *apb_data)
+{
+ struct device_node *np = dev->of_node;
+
+ /* fetch control signals */
+ apb_data->ctrl.wake_detect = of_get_named_gpio(np, "wake-detect-gpios", 0);
+ if (apb_data->ctrl.wake_detect < 0 ||
+ !gpio_is_valid(apb_data->ctrl.wake_detect)) {
+ dev_err(dev, "failed to get wake detect gpio\n");
+ return apb_data->ctrl.wake_detect;
+ }
+
+ apb_data->ctrl.reset = of_get_named_gpio(np, "reset-gpios", 0);
+ if (apb_data->ctrl.wake_detect < 0 ||
+ !gpio_is_valid(apb_data->ctrl.reset)) {
+ dev_err(dev, "failed to get wake detect gpio\n");
+ return apb_data->ctrl.wake_detect;
+ }
+
+ apb_data->ctrl.boot_ret = of_get_named_gpio(np, "boot-ret-gpios", 0);
+ if (apb_data->ctrl.boot_ret < 0 ||
+ !gpio_is_valid(apb_data->ctrl.boot_ret)) {
+ dev_err(dev, "failed to get boot retention gpio\n");
+ return apb_data->ctrl.boot_ret;
+ }
+
+ /* It's not mandetory to support power management interface */
+ apb_data->ctrl.pwroff = of_get_named_gpio(np, "pwr-off-gpios", 0);
+ if (apb_data->ctrl.pwroff < 0 ||
+ !gpio_is_valid(apb_data->ctrl.pwroff))
+ dev_info(dev, "failed to get power off gpio\n");
+
+ apb_data->ctrl.pwrdn = of_get_named_gpio(np, "pwr-down-gpios", 0);
+ if (apb_data->ctrl.pwrdn < 0 ||
+ !gpio_is_valid(apb_data->ctrl.pwrdn))
+ dev_info(dev, "failed to get power down gpio\n");
+
+ /* Regulators are optional, as we may have fixed supply coming in */
+ apb_data->vcore = devm_regulator_get(dev, "vcore");
+ if (IS_ERR_OR_NULL(apb_data->vcore)) {
+ dev_info(dev, "no core regulator found\n");
+ apb_data->vcore = NULL;
+ }
+
+ apb_data->vio = devm_regulator_get(dev, "vio");
+ if (IS_ERR_OR_NULL(apb_data->vio)) {
+ dev_info(dev, "no IO regulator found\n");
+ apb_data->vio = NULL;
+ }
+
+ apb_data->pinctrl = devm_pinctrl_get(dev);
+ if (IS_ERR(apb_data->pinctrl)) {
+ dev_err(dev, "could not get pinctrl handle\n");
+ return PTR_ERR(apb_data->pinctrl);
+ }
+ apb_data->pin_default = pinctrl_lookup_state(apb_data->pinctrl, "default");
+ if (IS_ERR(apb_data->pin_default)) {
+ dev_err(dev, "could not get default pin state\n");
+ return PTR_ERR(apb_data->pin_default);
+ }
+
+ return 0;
+}
+
+static int apb_ctrl_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct apb_ctrl_drvdata *apb_data;
+ int ret;
+
+ apb_data = devm_kzalloc(&pdev->dev, sizeof(*apb_data), GFP_KERNEL);
+ if (!apb_data)
+ return -ENOMEM;
+
+ ret = apb_ctrl_get_devtree_data(dev, apb_data);
+ if (ret) {
+ dev_err(dev, "failed to get devicetree data %d\n", ret);
+ return ret;
+ }
+
+ ret = apb_ctrl_init_seq(dev, apb_data);
+ if (ret) {
+ dev_err(dev, "failed to set init state of control signal %d\n",
+ ret);
+ goto exit;
+ }
+
+ platform_set_drvdata(pdev, apb_data);
+
+ apb_data->state = APB_STATE_OFF;
+ /*
+ * Assert AP module detect signal by pulling wake_detect low
+ */
+ deassert_wake(apb_data->ctrl.wake_detect);
+
+ /*
+ * In order to receive an interrupt, the GPIO must be set to input mode
+ *
+ * As per WDM spec, for the cold boot, the wake pulse must be
+ * >= 5000 usec, but at this stage it is power up sequence,
+ * so we always treat it as cold boot.
+ */
+ gpio_direction_input(apb_data->ctrl.wake_detect);
+
+ ret = devm_request_irq(dev, gpio_to_irq(apb_data->ctrl.wake_detect),
+ apb_ctrl_wake_detect_irq,
+ IRQF_TRIGGER_RISING,
+ "wake detect", apb_data);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to request wake detect IRQ\n");
+ goto exit;
+ }
+
+ /*
+ * Interrupt handling for WAKE_IN (from bridge) signal is required
+ *
+ * Assumption here is, AP already would have woken up and in the
+ * WAKE_IN/WAKE_FRAME event from bridge, as AP would pass-through event
+ * to SVC.
+ *
+ * Not sure anything else needs to take care here.
+ */
+ dev_err(dev, "Device registered successfully \n");
+ return 0;
+
+exit:
+ apb_ctrl_cleanup(apb_data);
+ return ret;
+}
+
+static int apb_ctrl_remove(struct platform_device *pdev)
+{
+ struct apb_ctrl_drvdata *apb_data = platform_get_drvdata(pdev);
+
+ if (apb_data)
+ apb_ctrl_cleanup(apb_data);
+
+ platform_set_drvdata(pdev, NULL);
+
+ return 0;
+}
+
+static int apb_ctrl_suspend(struct device *dev)
+{
+ /*
+ * If timing profile premits, we may shutdown bridge
+ * completely
+ *
+ * TODO: sequence ??
+ *
+ * Also, need to make sure we meet precondition for unipro suspend
+ * Precondition: Definition ???
+ */
+ return 0;
+}
+
+static int apb_ctrl_resume(struct device *dev)
+{
+ /*
+ * Atleast 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 SIMPLE_DEV_PM_OPS(apb_ctrl_pm_ops, apb_ctrl_suspend, apb_ctrl_resume);
+
+static struct of_device_id apb_ctrl_of_match[] = {
+ { .compatible = "usbffff,2", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, apb_ctrl_of_match);
+
+static struct platform_driver apb_ctrl_device_driver = {
+ .probe = apb_ctrl_probe,
+ .remove = apb_ctrl_remove,
+ .driver = {
+ .name = "unipro-APbridge",
+ .pm = &apb_ctrl_pm_ops,
+ .of_match_table = of_match_ptr(apb_ctrl_of_match),
+ }
+};
+
+module_platform_driver(apb_ctrl_device_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Vaibhav Hiremath <vaibhav.hiremath@linaro.org>");
+MODULE_DESCRIPTION("AP Bridge Control Driver for DB3 platform");
projects / mirror_ubuntu-bionic-kernel.git / commitdiff