docs: phy: place documentation under driver-api

This subsystem-specific documentation belongs to the
driver-api.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

1 files changed, 0 insertions, 137 deletions

diff --git a/Documentation/phy/samsung-usb2.rst b/Documentation/phy/samsung-usb2.rst
deleted file mode 100644
index c48c8b9797b9..000000000000
--- a/Documentation/phy/samsung-usb2.rst
+++ /dev/null
@@ -1,137 +0,0 @@
-====================================
-Samsung USB 2.0 PHY adaptation layer
-====================================
-
-1. Description
---------------
-
-The architecture of the USB 2.0 PHY module in Samsung SoCs is similar
-among many SoCs. In spite of the similarities it proved difficult to
-create a one driver that would fit all these PHY controllers. Often
-the differences were minor and were found in particular bits of the
-registers of the PHY. In some rare cases the order of register writes or
-the PHY powering up process had to be altered. This adaptation layer is
-a compromise between having separate drivers and having a single driver
-with added support for many special cases.
-
-2. Files description
---------------------
-
-- phy-samsung-usb2.c
-   This is the main file of the adaptation layer. This file contains
-   the probe function and provides two callbacks to the Generic PHY
-   Framework. This two callbacks are used to power on and power off the
-   phy. They carry out the common work that has to be done on all version
-   of the PHY module. Depending on which SoC was chosen they execute SoC
-   specific callbacks. The specific SoC version is selected by choosing
-   the appropriate compatible string. In addition, this file contains
-   struct of_device_id definitions for particular SoCs.
-
-- phy-samsung-usb2.h
-   This is the include file. It declares the structures used by this
-   driver. In addition it should contain extern declarations for
-   structures that describe particular SoCs.
-
-3. Supporting SoCs
-------------------
-
-To support a new SoC a new file should be added to the drivers/phy
-directory. Each SoC's configuration is stored in an instance of the
-struct samsung_usb2_phy_config::
-
-  struct samsung_usb2_phy_config {
-	const struct samsung_usb2_common_phy *phys;
-	int (*rate_to_clk)(unsigned long, u32 *);
-	unsigned int num_phys;
-	bool has_mode_switch;
-  };
-
-The num_phys is the number of phys handled by the driver. `*phys` is an
-array that contains the configuration for each phy. The has_mode_switch
-property is a boolean flag that determines whether the SoC has USB host
-and device on a single pair of pins. If so, a special register has to
-be modified to change the internal routing of these pins between a USB
-device or host module.
-
-For example the configuration for Exynos 4210 is following::
-
-  const struct samsung_usb2_phy_config exynos4210_usb2_phy_config = {
-	.has_mode_switch        = 0,
-	.num_phys		= EXYNOS4210_NUM_PHYS,
-	.phys			= exynos4210_phys,
-	.rate_to_clk		= exynos4210_rate_to_clk,
-  }
-
-- `int (*rate_to_clk)(unsigned long, u32 *)`
-
-	The rate_to_clk callback is to convert the rate of the clock
-	used as the reference clock for the PHY module to the value
-	that should be written in the hardware register.
-
-The exynos4210_phys configuration array is as follows::
-
-  static const struct samsung_usb2_common_phy exynos4210_phys[] = {
-	{
-		.label		= "device",
-		.id		= EXYNOS4210_DEVICE,
-		.power_on	= exynos4210_power_on,
-		.power_off	= exynos4210_power_off,
-	},
-	{
-		.label		= "host",
-		.id		= EXYNOS4210_HOST,
-		.power_on	= exynos4210_power_on,
-		.power_off	= exynos4210_power_off,
-	},
-	{
-		.label		= "hsic0",
-		.id		= EXYNOS4210_HSIC0,
-		.power_on	= exynos4210_power_on,
-		.power_off	= exynos4210_power_off,
-	},
-	{
-		.label		= "hsic1",
-		.id		= EXYNOS4210_HSIC1,
-		.power_on	= exynos4210_power_on,
-		.power_off	= exynos4210_power_off,
-	},
-	{},
-  };
-
-- `int (*power_on)(struct samsung_usb2_phy_instance *);`
-  `int (*power_off)(struct samsung_usb2_phy_instance *);`
-
-	These two callbacks are used to power on and power off the phy
-	by modifying appropriate registers.
-
-Final change to the driver is adding appropriate compatible value to the
-phy-samsung-usb2.c file. In case of Exynos 4210 the following lines were
-added to the struct of_device_id samsung_usb2_phy_of_match[] array::
-
-  #ifdef CONFIG_PHY_EXYNOS4210_USB2
-	{
-		.compatible = "samsung,exynos4210-usb2-phy",
-		.data = &exynos4210_usb2_phy_config,
-	},
-  #endif
-
-To add further flexibility to the driver the Kconfig file enables to
-include support for selected SoCs in the compiled driver. The Kconfig
-entry for Exynos 4210 is following::
-
-  config PHY_EXYNOS4210_USB2
-	bool "Support for Exynos 4210"
-	depends on PHY_SAMSUNG_USB2
-	depends on CPU_EXYNOS4210
-	help
-	  Enable USB PHY support for Exynos 4210. This option requires that
-	  Samsung USB 2.0 PHY driver is enabled and means that support for this
-	  particular SoC is compiled in the driver. In case of Exynos 4210 four
-	  phys are available - device, host, HSCI0 and HSCI1.
-
-The newly created file that supports the new SoC has to be also added to the
-Makefile. In case of Exynos 4210 the added line is following::
-
-  obj-$(CONFIG_PHY_EXYNOS4210_USB2)       += phy-exynos4210-usb2.o
-
-After completing these steps the support for the new SoC should be ready.