Re: [PATCH 8/8] phy: add driver for TI TUSB1210 ULPI PHY

[David Cohen <david.a.cohen@linux.intel.com>]

Hi Heikki,

On Fri, Jan 23, 2015 at 05:12:58PM +0200, Heikki Krogerus wrote:
> TUSB1210 ULPI PHY has vendor specific register for eye
> diagram tuning. On some platforms the system firmware has
> set optimized value to it. In order to not loose the
> optimized value, the driver stores it during probe and
> restores it every time the PHY is powered back on.
> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> Cc: Kishon Vijay Abraham I <kishon@ti.com>
> ---
>  drivers/phy/Kconfig        |   6 ++
>  drivers/phy/Makefile       |   1 +
>  drivers/phy/phy-tusb1210.c | 133 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 140 insertions(+)
>  create mode 100644 drivers/phy/phy-tusb1210.c
> 
> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
> index 26a7623..52ee720 100644
> --- a/drivers/phy/Kconfig
> +++ b/drivers/phy/Kconfig
> @@ -284,4 +284,10 @@ config PHY_QCOM_UFS
>  	help
>  	  Support for UFS PHY on QCOM chipsets.
>  
> +config PHY_TUSB1210
> +	tristate "TI TUSB1210 ULPI PHY module"
> +	depends on USB_ULPI_BUS
> +	help
> +	  Support for TI TUSB1210 USB ULPI PHY.
> +
>  endmenu
> diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
> index cfbb720..03f3d85 100644
> --- a/drivers/phy/Makefile
> +++ b/drivers/phy/Makefile
> @@ -37,3 +37,4 @@ obj-$(CONFIG_PHY_STIH41X_USB)		+= phy-stih41x-usb.o
>  obj-$(CONFIG_PHY_QCOM_UFS) 	+= phy-qcom-ufs.o
>  obj-$(CONFIG_PHY_QCOM_UFS) 	+= phy-qcom-ufs-qmp-20nm.o
>  obj-$(CONFIG_PHY_QCOM_UFS) 	+= phy-qcom-ufs-qmp-14nm.o
> +obj-$(CONFIG_PHY_TUSB1210)		+= phy-tusb1210.o
> diff --git a/drivers/phy/phy-tusb1210.c b/drivers/phy/phy-tusb1210.c
> new file mode 100644
> index 0000000..1551ae8
> --- /dev/null
> +++ b/drivers/phy/phy-tusb1210.c
> @@ -0,0 +1,133 @@
> +/**
> + * tusb1210.c - TUSB1210 USB ULPI PHY driver
> + *
> + * Copyright (C) 2015 Intel Corporation
> + *
> + * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +#include <linux/module.h>
> +#include <linux/ulpi/driver.h>
> +#include <linux/gpio/consumer.h>
> +
> +#include "ulpi_phy.h"
> +
> +#define TUSB1210_VENDOR_SPECIFIC2 0x80
> +
> +struct tusb1210 {
> +	struct ulpi *ulpi;
> +	struct phy *phy;
> +	struct gpio_desc *gpio_reset;
> +	struct gpio_desc *gpio_cs;
> +	u8 eye_diagram_tuning;
> +};
> +
> +static int tusb1210_power_on(struct phy *phy)
> +{
> +	struct tusb1210 *tusb = phy_get_drvdata(phy);
> +
> +	gpiod_set_value_cansleep(tusb->gpio_reset, 1);
> +	gpiod_set_value_cansleep(tusb->gpio_cs, 1);
> +
> +	/* Restore eye diagram optimisation value */
> +	ulpi_write(tusb->ulpi, TUSB1210_VENDOR_SPECIFIC2,
> +		   tusb->eye_diagram_tuning);

After you power on phy, ulpi bus may not be available right away. In
intel case, phy power on happens during dwc3 power on. ULPI bus is not
available until OTG controller and phy are in sync.

In resume, you can't restore eye diagram from here.

> +
> +	return 0;
> +}
> +
> +static int tusb1210_power_off(struct phy *phy)
> +{
> +	struct tusb1210 *tusb = phy_get_drvdata(phy);
> +
> +	gpiod_set_value_cansleep(tusb->gpio_reset, 0);
> +	gpiod_set_value_cansleep(tusb->gpio_cs, 0);
> +
> +	return 0;
> +}
> +
> +static struct phy_ops phy_ops = {
> +	.power_on = tusb1210_power_on,
> +	.power_off = tusb1210_power_off,
> +	.init = tusb1210_power_on,
> +	.exit = tusb1210_power_off,
> +	.owner = THIS_MODULE,
> +};
> +
> +static int tusb1210_probe(struct ulpi *ulpi)
> +{
> +	struct gpio_desc *gpio;
> +	struct tusb1210 *tusb;
> +	int ret;
> +
> +	tusb = devm_kzalloc(&ulpi->dev, sizeof(*tusb), GFP_KERNEL);
> +	if (!tusb)
> +		return -ENOMEM;
> +
> +	gpio = devm_gpiod_get(&ulpi->dev, "reset");
> +	if (!IS_ERR(gpio)) {
> +		ret = gpiod_direction_output(gpio, 0);
> +		if (ret)
> +			return ret;
> +		tusb->gpio_reset = gpio;
> +	}

You cannot proceed with probe if gpio reset is not available. Different
from CS, it's a mandatory pin to toggle in order to power on/off phy and
get it in sync with OTG controller.

> +
> +	gpio = devm_gpiod_get(&ulpi->dev, "cs");
> +	if (!IS_ERR(gpio)) {
> +		ret = gpiod_direction_output(gpio, 0);
> +		if (ret)
> +			return ret;
> +		tusb->gpio_cs = gpio;
> +	}
> +
> +	/* Store initial eye diagram optimisation value */
> +	ret = ulpi_read(ulpi, TUSB1210_VENDOR_SPECIFIC2);

It's unclear if ulpi is accessible at this point. You can't read it at
this point.

Br, David

> +	if (ret < 0)
> +		return ret;
> +
> +	tusb->eye_diagram_tuning = ret;
> +
> +	tusb->phy = ulpi_phy_create(ulpi, &phy_ops);
> +	if (IS_ERR(tusb->phy))
> +		return PTR_ERR(tusb->phy);
> +
> +	tusb->ulpi = ulpi;
> +
> +	phy_set_drvdata(tusb->phy, tusb);
> +	ulpi_set_drvdata(ulpi, tusb);
> +	return 0;
> +}
> +
> +static void tusb1210_remove(struct ulpi *ulpi)
> +{
> +	struct tusb1210 *tusb = ulpi_get_drvdata(ulpi);
> +
> +	ulpi_phy_destroy(ulpi, tusb->phy);
> +}
> +
> +#define TI_VENDOR_ID 0x0451
> +
> +static const struct ulpi_device_id tusb1210_ulpi_id[] = {
> +	{ TI_VENDOR_ID, 0x1508, },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(ulpi, tusb1210_ulpi_id);
> +
> +static struct ulpi_driver tusb1210_driver = {
> +	.id_table = tusb1210_ulpi_id,
> +	.probe = tusb1210_probe,
> +	.remove = tusb1210_remove,
> +	.driver = {
> +		.name = "tusb1210",
> +		.owner = THIS_MODULE,
> +	},
> +};
> +
> +module_ulpi_driver(tusb1210_driver);
> +
> +MODULE_AUTHOR("Intel Corporation");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("TUSB1210 ULPI PHY driver");
> -- 
> 2.1.4
> 
> --
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