phy: Add a driver for dm816x USB PHY

Add a minimal driver for dm816x USB. This makes USB work on dm816x
without any other changes needed as it can use the existing musb_dsps
glue layer for the USB controller.

Note that this phy is different from dm814x and am335x.

Cc: Bin Liu <binmlist@gmail.com>
Cc: Brian Hutchinson <b.hutchman@gmail.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Matthijs van Duin <matthijsvanduin@gmail.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

3 files changed, 298 insertions, 0 deletions

diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
index 2962de205ba7..885c39c28a8b 100644
--- a/drivers/phy/Kconfig
+++ b/drivers/phy/Kconfig
@@ -35,6 +35,13 @@ config ARMADA375_USBCLUSTER_PHY
         depends on OF
         select GENERIC_PHY
 
+config PHY_DM816X_USB
+        tristate "TI dm816x USB PHY driver"
+        depends on ARCH_OMAP2PLUS
+        select GENERIC_PHY
+        help
+          Enable this for dm816x USB to work.
+
 config PHY_EXYNOS_MIPI_VIDEO
         tristate "S5P/EXYNOS SoC series MIPI CSI-2/DSI PHY driver"
         depends on HAS_IOMEM
diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
index f080e1bb2a74..dab6665ad9c1 100644
--- a/drivers/phy/Makefile
+++ b/drivers/phy/Makefile
@@ -5,6 +5,7 @@
 obj-$(CONFIG_GENERIC_PHY)               += phy-core.o
 obj-$(CONFIG_PHY_BERLIN_USB)            += phy-berlin-usb.o
 obj-$(CONFIG_PHY_BERLIN_SATA)           += phy-berlin-sata.o
+obj-$(CONFIG_PHY_DM816X_USB)            += phy-dm816x-usb.o
 obj-$(CONFIG_ARMADA375_USBCLUSTER_PHY)  += phy-armada375-usb2.o
 obj-$(CONFIG_BCM_KONA_USB2_PHY)         += phy-bcm-kona-usb2.o
 obj-$(CONFIG_PHY_EXYNOS_DP_VIDEO)       += phy-exynos-dp-video.o
diff --git a/drivers/phy/phy-dm816x-usb.c b/drivers/phy/phy-dm816x-usb.c
new file mode 100644
index 000000000000..7b42555ddd51
--- /dev/null
+++ b/drivers/phy/phy-dm816x-usb.c
@@ -0,0 +1,290 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/usb/phy_companion.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/pm_runtime.h>
+#include <linux/delay.h>
+#include <linux/phy/phy.h>
+#include <linux/of_platform.h>
+
+#include <linux/mfd/syscon.h>
+
+/*
+ * TRM has two sets of USB_CTRL registers.. The correct register bits
+ * are in TRM section 24.9.8.2 USB_CTRL Register. The TRM documents the
+ * phy as being SR70LX Synopsys USB 2.0 OTG nanoPHY. It also seems at
+ * least dm816x rev c ignores writes to USB_CTRL register, but the TI
+ * kernel is writing to those so it's possible that later revisions
+ * have worknig USB_CTRL register.
+ *
+ * Also note that At least USB_CTRL register seems to be dm816x specific
+ * according to the TRM. It's possible that USBPHY_CTRL is more generic,
+ * but that would have to be checked against the SR70LX documentation
+ * which does not seem to be publicly available.
+ *
+ * Finally, the phy on dm814x and am335x is different from dm816x.
+ */
+#define DM816X_USB_CTRL_PHYCLKSRC       BIT(8)  /* 1 = PLL ref clock */
+#define DM816X_USB_CTRL_PHYSLEEP1       BIT(1)  /* Enable the first phy */
+#define DM816X_USB_CTRL_PHYSLEEP0       BIT(0)  /* Enable the second phy */
+
+#define DM816X_USBPHY_CTRL_TXRISETUNE   1
+#define DM816X_USBPHY_CTRL_TXVREFTUNE   0xc
+#define DM816X_USBPHY_CTRL_TXPREEMTUNE  0x2
+
+struct dm816x_usb_phy {
+        struct regmap *syscon;
+        struct device *dev;
+        unsigned int instance;
+        struct clk *refclk;
+        struct usb_phy phy;
+        unsigned int usb_ctrl;          /* Shared between phy0 and phy1 */
+        unsigned int usbphy_ctrl;
+};
+
+static int dm816x_usb_phy_set_host(struct usb_otg *otg, struct usb_bus *host)
+{
+        otg->host = host;
+        if (!host)
+                otg->state = OTG_STATE_UNDEFINED;
+
+        return 0;
+}
+
+static int dm816x_usb_phy_set_peripheral(struct usb_otg *otg,
+                                         struct usb_gadget *gadget)
+{
+        otg->gadget = gadget;
+        if (!gadget)
+                otg->state = OTG_STATE_UNDEFINED;
+
+        return 0;
+}
+
+static int dm816x_usb_phy_init(struct phy *x)
+{
+        struct dm816x_usb_phy *phy = phy_get_drvdata(x);
+        unsigned int val;
+        int error;
+
+        if (clk_get_rate(phy->refclk) != 24000000)
+                dev_warn(phy->dev, "nonstandard phy refclk\n");
+
+        /* Set PLL ref clock and put phys to sleep */
+        error = regmap_update_bits(phy->syscon, phy->usb_ctrl,
+                                   DM816X_USB_CTRL_PHYCLKSRC |
+                                   DM816X_USB_CTRL_PHYSLEEP1 |
+                                   DM816X_USB_CTRL_PHYSLEEP0,
+                                   0);
+        regmap_read(phy->syscon, phy->usb_ctrl, &val);
+        if ((val & 3) != 0)
+                dev_info(phy->dev,
+                         "Working dm816x USB_CTRL! (0x%08x)\n",
+                         val);
+
+        /*
+         * TI kernel sets these values for "symmetrical eye diagram and
+         * better signal quality" so let's assume somebody checked the
+         * values with a scope and set them here too.
+         */
+        regmap_read(phy->syscon, phy->usbphy_ctrl, &val);
+        val |= DM816X_USBPHY_CTRL_TXRISETUNE |
+                DM816X_USBPHY_CTRL_TXVREFTUNE |
+                DM816X_USBPHY_CTRL_TXPREEMTUNE;
+        regmap_write(phy->syscon, phy->usbphy_ctrl, val);
+
+        return 0;
+}
+
+static struct phy_ops ops = {
+        .init           = dm816x_usb_phy_init,
+        .owner          = THIS_MODULE,
+};
+
+static int dm816x_usb_phy_runtime_suspend(struct device *dev)
+{
+        struct dm816x_usb_phy *phy = dev_get_drvdata(dev);
+        unsigned int mask, val;
+        int error = 0;
+
+        mask = BIT(phy->instance);
+        val = ~BIT(phy->instance);
+        error = regmap_update_bits(phy->syscon, phy->usb_ctrl,
+                                   mask, val);
+        if (error)
+                dev_err(phy->dev, "phy%i failed to power off\n",
+                        phy->instance);
+        clk_disable(phy->refclk);
+
+        return 0;
+}
+
+static int dm816x_usb_phy_runtime_resume(struct device *dev)
+{
+        struct dm816x_usb_phy *phy = dev_get_drvdata(dev);
+        unsigned int mask, val;
+        int error;
+
+        error = clk_enable(phy->refclk);
+        if (error)
+                return error;
+
+        /*
+         * Note that at least dm816x rev c does not seem to do
+         * anything with the USB_CTRL register. But let's follow
+         * what the TI tree is doing in case later revisions use
+         * USB_CTRL.
+         */
+        mask = BIT(phy->instance);
+        val = BIT(phy->instance);
+        error = regmap_update_bits(phy->syscon, phy->usb_ctrl,
+                                   mask, val);
+        if (error) {
+                dev_err(phy->dev, "phy%i failed to power on\n",
+                        phy->instance);
+                clk_disable(phy->refclk);
+                return error;
+        }
+
+        return 0;
+}
+
+static UNIVERSAL_DEV_PM_OPS(dm816x_usb_phy_pm_ops,
+                            dm816x_usb_phy_runtime_suspend,
+                            dm816x_usb_phy_runtime_resume,
+                            NULL);
+
+#ifdef CONFIG_OF
+static const struct of_device_id dm816x_usb_phy_id_table[] = {
+        {
+                .compatible = "ti,dm8168-usb-phy",
+        },
+        {},
+};
+MODULE_DEVICE_TABLE(of, dm816x_usb_phy_id_table);
+#endif
+
+static int dm816x_usb_phy_probe(struct platform_device *pdev)
+{
+        struct dm816x_usb_phy *phy;
+        struct resource *res;
+        struct phy *generic_phy;
+        struct phy_provider *phy_provider;
+        struct usb_otg *otg;
+        const struct of_device_id *of_id;
+        const struct usb_phy_data *phy_data;
+        int error;
+
+        of_id = of_match_device(of_match_ptr(dm816x_usb_phy_id_table),
+                                &pdev->dev);
+        if (!of_id)
+                return -EINVAL;
+
+        phy = devm_kzalloc(&pdev->dev, sizeof(*phy), GFP_KERNEL);
+        if (!phy)
+                return -ENOMEM;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!res)
+                return -ENOENT;
+
+        phy->syscon = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
+                                                      "syscon");
+        if (IS_ERR(phy->syscon))
+                return PTR_ERR(phy->syscon);
+
+        /*
+         * According to sprs614e.pdf, the first usb_ctrl is shared and
+         * the second instance for usb_ctrl is reserved.. Also the
+         * register bits are different from earlier TRMs.
+         */
+        phy->usb_ctrl = 0x20;
+        phy->usbphy_ctrl = (res->start & 0xff) + 4;
+        if (phy->usbphy_ctrl == 0x2c)
+                phy->instance = 1;
+
+        phy_data = of_id->data;
+
+        otg = devm_kzalloc(&pdev->dev, sizeof(*otg), GFP_KERNEL);
+        if (!otg)
+                return -ENOMEM;
+
+        phy->dev = &pdev->dev;
+        phy->phy.dev = phy->dev;
+        phy->phy.label = "dm8168_usb_phy";
+        phy->phy.otg = otg;
+        phy->phy.type = USB_PHY_TYPE_USB2;
+        otg->set_host = dm816x_usb_phy_set_host;
+        otg->set_peripheral = dm816x_usb_phy_set_peripheral;
+        otg->usb_phy = &phy->phy;
+
+        platform_set_drvdata(pdev, phy);
+
+        phy->refclk = devm_clk_get(phy->dev, "refclk");
+        if (IS_ERR(phy->refclk))
+                return PTR_ERR(phy->refclk);
+        error = clk_prepare(phy->refclk);
+        if (error)
+                return error;
+
+        pm_runtime_enable(phy->dev);
+        generic_phy = devm_phy_create(phy->dev, NULL, &ops);
+        if (IS_ERR(generic_phy))
+                return PTR_ERR(generic_phy);
+
+        phy_set_drvdata(generic_phy, phy);
+
+        phy_provider = devm_of_phy_provider_register(phy->dev,
+                                                     of_phy_simple_xlate);
+        if (IS_ERR(phy_provider))
+                return PTR_ERR(phy_provider);
+
+        usb_add_phy_dev(&phy->phy);
+
+        return 0;
+}
+
+static int dm816x_usb_phy_remove(struct platform_device *pdev)
+{
+        struct dm816x_usb_phy *phy = platform_get_drvdata(pdev);
+
+        usb_remove_phy(&phy->phy);
+        pm_runtime_disable(phy->dev);
+        clk_unprepare(phy->refclk);
+
+        return 0;
+}
+
+static struct platform_driver dm816x_usb_phy_driver = {
+        .probe          = dm816x_usb_phy_probe,
+        .remove         = dm816x_usb_phy_remove,
+        .driver         = {
+                .name   = "dm816x-usb-phy",
+                .pm     = &dm816x_usb_phy_pm_ops,
+                .of_match_table = of_match_ptr(dm816x_usb_phy_id_table),
+        },
+};
+
+module_platform_driver(dm816x_usb_phy_driver);
+
+MODULE_ALIAS("platform:dm816x_usb");
+MODULE_AUTHOR("Tony Lindgren <tony@atomide.com>");
+MODULE_DESCRIPTION("dm816x usb phy driver");
+MODULE_LICENSE("GPL v2");