[PATCH v2 2/3] phy: Add driver for ST-Ericsson AB8500 USB PHY

[Stephan Gerhold]

The AB8500 PMIC contains an USB PHY that needs to be set up in
device or host mode to make USB work properly. Add a simple driver
for the generic PHY uclass that allows enabling it.

The if (CONFIG_IS_ENABLED(USB_MUSB_HOST)) might be a bit strange.
The USB PHY must be configured in either host or device mode and
somehow the USB PHY driver must be made aware of the mode.

Actually, the MUSB driver used together with this PHY does not
support dynamic selection of host/device mode in U-Boot at the moment.
Therefore, one very simple approach that works fine is to select
the mode to configure at compile time. When the MUSB driver is
configured in host mode the PHY is configured in host mode, and
similarly when the MUSB driver is configured in device/gadget mode.

Reviewed-by: Linus Walleij <linus.walleij at linaro.org>
Signed-off-by: Stephan Gerhold <stephan at gerhold.net>
---

Changes in v2:
- Assign AB8500_BIT_PHY_CTRL_DEVICE_EN by default and only replace
  it with AB8500_BIT_PHY_CTRL_HOST_EN if needed (Jaehoon Chung)

Better suggestions to make the USB PHY driver aware of the mode
are very welcome. :) I'm not sure it's worth it though, the compile
time selection is not ideal but it does the job just fine for now.

---
 drivers/phy/Kconfig          |  6 +++++
 drivers/phy/Makefile         |  1 +
 drivers/phy/phy-ab8500-usb.c | 52 ++++++++++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+)
 create mode 100644 drivers/phy/phy-ab8500-usb.c

diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
index 008186a10d..92c74b9d0b 100644
--- a/drivers/phy/Kconfig
+++ b/drivers/phy/Kconfig
@@ -64,6 +64,12 @@ config MIPI_DPHY_HELPERS
 	help
 	  Provides a number of helpers a core functions for MIPI D-PHY drivers.
 
+config AB8500_USB_PHY
+	bool "AB8500 USB PHY Driver"
+	depends on PHY && PMIC_AB8500
+	help
+	  Support for the USB OTG PHY in ST-Ericsson AB8500.
+
 config BCM6318_USBH_PHY
 	bool "BCM6318 USBH PHY support"
 	depends on PHY && ARCH_BMIPS
diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
index 3c4a673a83..bf03d05d9b 100644
--- a/drivers/phy/Makefile
+++ b/drivers/phy/Makefile
@@ -6,6 +6,7 @@
 obj-$(CONFIG_$(SPL_)PHY) += phy-uclass.o
 obj-$(CONFIG_$(SPL_)NOP_PHY) += nop-phy.o
 obj-$(CONFIG_MIPI_DPHY_HELPERS) += phy-core-mipi-dphy.o
+obj-$(CONFIG_AB8500_USB_PHY) += phy-ab8500-usb.o
 obj-$(CONFIG_BCM6318_USBH_PHY) += bcm6318-usbh-phy.o
 obj-$(CONFIG_BCM6348_USBH_PHY) += bcm6348-usbh-phy.o
 obj-$(CONFIG_BCM6358_USBH_PHY) += bcm6358-usbh-phy.o
diff --git a/drivers/phy/phy-ab8500-usb.c b/drivers/phy/phy-ab8500-usb.c
new file mode 100644
index 0000000000..0e04595717
--- /dev/null
+++ b/drivers/phy/phy-ab8500-usb.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* Copyright (C) 2019 Stephan Gerhold */
+
+#include <common.h>
+#include <dm.h>
+#include <generic-phy.h>
+#include <linux/bitops.h>
+#include <power/pmic.h>
+#include <power/ab8500.h>
+
+#define AB8500_USB_PHY_CTRL_REG			AB8500_USB(0x8A)
+#define AB8500_BIT_PHY_CTRL_HOST_EN		BIT(0)
+#define AB8500_BIT_PHY_CTRL_DEVICE_EN		BIT(1)
+#define AB8500_USB_PHY_CTRL_MASK		(AB8500_BIT_PHY_CTRL_HOST_EN |\
+						 AB8500_BIT_PHY_CTRL_DEVICE_EN)
+
+static int ab8500_usb_phy_power_on(struct phy *phy)
+{
+	struct udevice *dev = phy->dev;
+	uint set = AB8500_BIT_PHY_CTRL_DEVICE_EN;
+
+	if (CONFIG_IS_ENABLED(USB_MUSB_HOST))
+		set = AB8500_BIT_PHY_CTRL_HOST_EN;
+
+	return pmic_clrsetbits(dev->parent, AB8500_USB_PHY_CTRL_REG,
+			       AB8500_USB_PHY_CTRL_MASK, set);
+}
+
+static int ab8500_usb_phy_power_off(struct phy *phy)
+{
+	struct udevice *dev = phy->dev;
+
+	return pmic_clrsetbits(dev->parent, AB8500_USB_PHY_CTRL_REG,
+			       AB8500_USB_PHY_CTRL_MASK, 0);
+}
+
+struct phy_ops ab8500_usb_phy_ops = {
+	.power_on = ab8500_usb_phy_power_on,
+	.power_off = ab8500_usb_phy_power_off,
+};
+
+static const struct udevice_id ab8500_usb_phy_ids[] = {
+	{ .compatible = "stericsson,ab8500-usb" },
+	{ }
+};
+
+U_BOOT_DRIVER(ab8500_usb_phy) = {
+	.name = "ab8500_usb_phy",
+	.id = UCLASS_PHY,
+	.of_match = ab8500_usb_phy_ids,
+	.ops = &ab8500_usb_phy_ops,
+};
-- 
2.32.0