Commit af3aae10 authored by Vaibhav Hiremath's avatar Vaibhav Hiremath Committed by Greg Kroah-Hartman
Browse files

greybus: arche-apb-ctrl: Introduce ara,init-disable property for APB 



New DT property "ara,init-disable" will allow user to disable
APB1 or APB2 during boot and enable it only when needed through
command prompt via sysfs interface.

 - To disable APB2 during boot, specify "ara,init-disable" property in
   respective APB node.

 - How to check the state
   # cat /sys/devices/arche_platform.*/apb*/state

   It should be 'off', if 'ara,init-disable' enabled in DT.

 - During runtime if user/developer desired to enable APB2 (strictly and
   only for development purpose) then respective APB can be enabled
   through,

   # echo active > /sys/devices/arche_platform.*/apb*/state

Note:
  - If APB device is in 'off,disabled' state, then no state transitions
    are permitted.
  - User/developer must first activate APB device

    # echo active > /sys/devices/arche_platform.*/apb*/state

    This will clear the 'init-disable' flag and allow state transition
    from here onwards.
    Note that, 'off,disabled' is only indicative state and is only
    applicable during init/boot.

Testing Done: Tested on EVT1.2 and DB3.5 platform

Signed-off-by: default avatarVaibhav Hiremath <vaibhav.hiremath@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent 33d76291

drivers/staging/greybus/arche-apb-ctrl.c

+23 −1
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ struct arche_apb_ctrl_drvdata { 
	int pwrdn_gpio;



	enum arche_platform_state state;

	bool init_disabled;



	struct regulator *vcore;

	struct regulator *vio;
@@ -77,6 +78,9 @@ static int apb_ctrl_coldboot_seq(struct platform_device *pdev) 
	struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev);

	int ret;



	if (apb->init_disabled)

		return 0;



	/* Hold APB in reset state */

	assert_reset(apb->resetn_gpio);
@@ -119,6 +123,9 @@ static int apb_ctrl_fw_flashing_seq(struct platform_device *pdev) 
	struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev);

	int ret;



	if (apb->init_disabled)

		return 0;



	ret = regulator_enable(apb->vcore);

	if (ret) {

		dev_err(dev, "failed to enable core regulator\n");
@@ -142,6 +149,9 @@ static int apb_ctrl_standby_boot_seq(struct platform_device *pdev) 
{

	struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev);



	if (apb->init_disabled)

		return 0;



	/* If it is in OFF state, then we do not want to change the state */

	if (apb->state == ARCHE_PLATFORM_STATE_OFF)

		return 0;
@@ -163,6 +173,9 @@ static void apb_ctrl_poweroff_seq(struct platform_device *pdev) 
{

	struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev);



	if (apb->init_disabled)

		return;



	/* disable the clock */

	if (gpio_is_valid(apb->clk_en_gpio))

		gpio_set_value(apb->clk_en_gpio, 0);
@@ -186,6 +199,7 @@ static ssize_t state_store(struct device *dev, 
	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)
@@ -197,7 +211,11 @@ static ssize_t state_store(struct device *dev, 
			return count;



		apb_ctrl_poweroff_seq(pdev);

		is_disabled = apb->init_disabled;

		apb->init_disabled = false;

		ret = apb_ctrl_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;
@@ -226,7 +244,8 @@ static ssize_t state_show(struct device *dev, 


	switch (apb->state) {

	case ARCHE_PLATFORM_STATE_OFF:

		return sprintf(buf, "off\n");

		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:
@@ -346,6 +365,9 @@ int arche_apb_ctrl_probe(struct platform_device *pdev) 


	/* 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, "ara,init-disable"))

		apb->init_disabled = true;



	platform_set_drvdata(pdev, apb);