drivers: phy: add generic PHY framework

The PHY framework provides a set of APIs to control a PHY. This API is
derived from the linux version of the generic PHY framework.
Currently the API supports init(), deinit(), power_on, power_off() and
reset(). The framework provides a way to get a reference to a phy from the
device-tree.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

include/generic-phy.h

@@ -0,0 +1,224 @@
+/*
+ * Copyright (C) 2017 Texas Instruments Incorporated - http://www.ti.com/
+ * Written by Jean-Jacques Hiblot  <jjhiblot@ti.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __GENERIC_PHY_H
+#define __GENERIC_PHY_H
+
+
+/**
+ * struct phy - A handle to (allowing control of) a single phy port.
+ *
+ * Clients provide storage for phy handles. The content of the structure is
+ * managed solely by the PHY API and PHY drivers. A phy struct is
+ * initialized by "get"ing the phy struct. The phy struct is passed to all
+ * other phy APIs to identify which PHY port to operate upon.
+ *
+ * @dev: The device which implements the PHY port.
+ * @id: The PHY ID within the provider.
+ *
+ */
+struct phy {
+	struct udevice *dev;
+	unsigned long id;
+};
+
+/*
+ * struct udevice_ops - set of function pointers for phy operations
+ * @init: operation to be performed for initializing phy (optional)
+ * @exit: operation to be performed while exiting (optional)
+ * @reset: reset the phy (optional).
+ * @power_on: powering on the phy (optional)
+ * @power_off: powering off the phy (optional)
+ */
+struct phy_ops {
+	/**
+	 * of_xlate - Translate a client's device-tree (OF) phy specifier.
+	 *
+	 * The PHY core calls this function as the first step in implementing
+	 * a client's generic_phy_get_by_*() call.
+	 *
+	 * If this function pointer is set to NULL, the PHY core will use a
+	 * default implementation, which assumes #phy-cells = <0> or
+	 * #phy-cells = <1>, and in the later case that the DT cell
+	 * contains a simple integer PHY port ID.
+	 *
+	 * @phy:	The phy struct to hold the translation result.
+	 * @args:	The phy specifier values from device tree.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int	(*of_xlate)(struct phy *phy,
+			struct fdtdec_phandle_args *args);
+
+	/**
+	 * init - initialize the hardware.
+	 *
+	 * Hardware intialization should not be done in during probe() but
+	 * should be implemented in this init() function. It could be starting
+	 * PLL, taking a controller out of reset, routing, etc. This function
+	 * is typically called only once per PHY port.
+	 * If power_on() is not implemented, it must power up the phy.
+	 *
+	 * @phy:	the PHY port to initialize
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int	(*init)(struct phy *phy);
+
+	/**
+	* exit - de-initialize the PHY device
+	*
+	* Hardware de-intialization should be done here. Every step done in
+	* init() should be undone here.
+	* This could be used to suspend the phy to reduce power consumption or
+	* to put the phy in a known condition before booting the OS (though it
+	* is NOT called automatically before booting the OS)
+	* If power_off() is not implemented, it must power down the phy.
+	*
+	* @phy:	PHY port to be de-initialized
+	* @return 0 if OK, or a negative error code
+	*/
+	int	(*exit)(struct phy *phy);
+
+	/**
+	* reset - resets a PHY device without shutting down
+	*
+	* @phy:	PHY port to be reset
+	*
+	* During runtime, the PHY may need to be reset in order to
+	* re-establish connection etc without being shut down or exit.
+	*
+	* @return 0 if OK, or a negative error code
+	*/
+	int	(*reset)(struct phy *phy);
+
+	/**
+	* power_on - power on a PHY device
+	*
+	* @phy:	PHY port to be powered on
+	*
+	* During runtime, the PHY may need to be powered on or off several
+	* times. This function is used to power on the PHY. It relies on the
+	* setup done in init(). If init() is not implemented, it must take care
+	* of setting up the context (PLLs, ...)
+	*
+	* @return 0 if OK, or a negative error code
+	*/
+	int	(*power_on)(struct phy *phy);
+
+	/**
+	* power_off - power off a PHY device
+	*
+	* @phy:	PHY port to be powered off
+	*
+	* During runtime, the PHY may need to be powered on or off several
+	* times. This function is used to power off the PHY. Except if
+	* init()/deinit() are not implemented, it must not de-initialize
+	* everything.
+	*
+	* @return 0 if OK, or a negative error code
+	*/
+	int	(*power_off)(struct phy *phy);
+};
+
+
+/**
+ * generic_phy_init() - initialize the PHY port
+ *
+ * @phy:	the PHY port to initialize
+ * @return 0 if OK, or a negative error code
+ */
+int generic_phy_init(struct phy *phy);
+
+/**
+ * generic_phy_init() - de-initialize the PHY device
+ *
+ * @phy:	PHY port to be de-initialized
+ * @return 0 if OK, or a negative error code
+ */
+int generic_phy_exit(struct phy *phy);
+
+/**
+ * generic_phy_reset() - resets a PHY device without shutting down
+ *
+ * @phy:	PHY port to be reset
+ *@return 0 if OK, or a negative error code
+ */
+int generic_phy_reset(struct phy *phy);
+
+/**
+ * generic_phy_power_on() - power on a PHY device
+ *
+ * @phy:	PHY port to be powered on
+ * @return 0 if OK, or a negative error code
+ */
+int generic_phy_power_on(struct phy *phy);
+
+/**
+ * generic_phy_power_off() - power off a PHY device
+ *
+ * @phy:	PHY port to be powered off
+ * @return 0 if OK, or a negative error code
+ */
+int generic_phy_power_off(struct phy *phy);
+
+
+/**
+ * generic_phy_get_by_index() - Get a PHY device by integer index.
+ *
+ * @user:	the client device
+ * @index:	The index in the list of available PHYs
+ * @phy:	A pointer to the PHY port
+ *
+ * This looks up a PHY device for a client device based on its position in the
+ * list of the possible PHYs.
+ *
+ * example:
+ * usb1: usb_otg_ss@xxx {
+ *       compatible = "xxx";
+ *       reg = <xxx>;
+ *   .
+ *   .
+ *   phys = <&usb2_phy>, <&usb3_phy>;
+ *   .
+ *   .
+ * };
+ * the USB2 phy can be accessed by passing index '0' and the USB3 phy can
+ * be accessed by passing index '1'
+ *
+ * @return 0 if OK, or a negative error code
+ */
+int generic_phy_get_by_index(struct udevice *user, int index,
+			     struct phy *phy);
+
+/**
+ * generic_phy_get_by_name() - Get a PHY device by its name.
+ *
+ * @user:	the client device
+ * @phy_name:	The name of the PHY in the list of possible PHYs
+ * @phy:	A pointer to the PHY port
+ *
+ * This looks up a PHY device for a client device in the
+ * list of the possible PHYs based on its name.
+ *
+ * example:
+ * usb1: usb_otg_ss@xxx {
+ *       compatible = "xxx";
+ *       reg = <xxx>;
+ *   .
+ *   .
+ *   phys = <&usb2_phy>, <&usb3_phy>;
+ *   phy-names = "usb2phy", "usb3phy";
+ *   .
+ *   .
+ * };
+ * the USB3 phy can be accessed using "usb3phy", and USB2 by using "usb2phy"
+ *
+ * @return 0 if OK, or a negative error code
+ */
+int generic_phy_get_by_name(struct udevice *user, const char *phy_name,
+			    struct phy *phy);
+
+#endif /*__GENERIC_PHY_H */