Re: [PATCH] phy: Add a driver for dm816x USB PHY

[Kishon Vijay Abraham I <kishon@ti.com>]

Hi Tony,

On Tuesday 10 March 2015 02:21 AM, Tony Lindgren wrote:
> Add a minimal driver for dm816x USB. Otherwise we can just use
> the existing musb_am335x and musb_dsps on dm816x.

If we can use an existing driver, I'd prefer that.
>
> Cc: Brian Hutchinson <b.hutchman@gmail.com>
> Cc: Felipe Balbi <balbi@ti.com>
> Signed-off-by: Tony Lindgren <tony@atomide.com>
>
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/phy/dm816x-phy.txt
> @@ -0,0 +1,24 @@
> +Device tree binding documentation for am816x USB PHY
> +=========================
> +
> +Required properties:
> +- compatible : should be "ti,dm816x-usb-phy"
> +- reg : offset and length of the PHY register set.
> +- reg-names : name for the phy registers
> +- clocks : phandle to the clock
> +- clock-names : name of the clock
> +- syscon: phandle for the syscon node to access misc registers
> +- #phy-cells : from the generic PHY bindings, must be 1
> +- syscon: phandle for the syscon node to access misc registers
> +
> +Example:
> +
> +usb_phy0: usb-phy@20 {
> +	compatible = "ti,dm8168-usb-phy";
> +	reg = <0x20 0x8>;
> +	reg-names = "phy";
> +	clocks = <&main_fapll 6>;
> +	clock-names = "refclk";
> +	#phy-cells = <0>;
> +	syscon = <&scm_conf>;
> +};
> --- 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 dm81xx USB to work."
> +
>   config PHY_EXYNOS_MIPI_VIDEO
>   	tristate "S5P/EXYNOS SoC series MIPI CSI-2/DSI PHY driver"
>   	depends on HAS_IOMEM
> --- 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
> --- /dev/null
> +++ b/drivers/phy/phy-dm816x-usb.c
> @@ -0,0 +1,295 @@
> +/*
> + * 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; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; 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.
> + */
> +#define DM816X_USB_CTRL_PHYCLKSRC	BIT(8)	/* 1 = PLL ref clock */
> +#define DM816X_USB_CTRL_PHYSLEEP1	BIT(1)
> +#define DM816X_USB_CTRL_PHYSLEEP0	BIT(0)
> +
> +#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_power_off(struct phy *x)
> +{
> +	struct dm816x_usb_phy *phy = phy_get_drvdata(x);
> +
> +	pm_runtime_put(phy->dev);

phy core takes care of invoking pm_runtime_put on power_off.
So this function shouldn't be needed at all.
> +
> +	return 0;
> +}
> +
> +static int dm816x_usb_phy_power_on(struct phy *x)
> +{
> +	struct dm816x_usb_phy *phy = phy_get_drvdata(x);
> +
> +	return pm_runtime_get_sync(phy->dev);

similarly on power_on, phy_core invokes pm_runtime_get_sync.
> +}
> +
> +static int dm816x_usb_phy_init(struct phy *x)
> +{
> +	struct dm816x_usb_phy *phy = phy_get_drvdata(x);
> +	unsigned int val;
> +	int error;
> +
> +	error = pm_runtime_get_sync(phy->dev);
> +	if (error)
> +		return error;

not required.
> +
> +	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);
> +
> +	/*
> +	 * 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);
> +
> +	pm_runtime_put(phy->dev);

same here.
> +
> +	return 0;
> +}
> +
> +static struct phy_ops ops = {
> +	.init		= dm816x_usb_phy_init,
> +	.power_on	= dm816x_usb_phy_power_on,
> +	.power_off	= dm816x_usb_phy_power_off,
> +	.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;
> +
> +	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);
> +
> +	generic_phy = devm_phy_create(phy->dev, NULL, &ops);
> +	if (IS_ERR(generic_phy))
> +		return PTR_ERR(generic_phy);

Just invoke pm_runtime_enable before phy_create and phy core will take care of
invoking all pm_runtime functions at appropriate time.

Cheers
Kishon