Re: [PATCH 2/2] phy: meson: add USB2 PHY support for Meson GXL and GXM

["Hendrik v. Raven" <hendrik@consetetur.de>]

Currently just trying to learn by reading, but a minor comment inline.

On Sat, Mar 04, 2017 at 11:22:31PM +0100, Martin Blumenstingl wrote:
> This adds a new driver for the USB2 PHYs found on Meson GXL and GXM SoCs
> (both SoCs are using the same USB PHY register layout).
> 
> The USB2 PHY is a simple PHY which only has a few registers to configure
> the mode (host/device) and a reset register (to enable/disable the PHY).
> 
> Unfortunately there are no datasheets available for any of these PHYs.
> Both drivers were written by reading the reference drivers provided by
> Amlogic and analyzing the registers on the kernel that was shipped on
> the boards I have.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> ---
>  drivers/phy/Kconfig              |  13 ++
>  drivers/phy/Makefile             |   1 +
>  drivers/phy/phy-meson-gxl-usb2.c | 263 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 277 insertions(+)
>  create mode 100644 drivers/phy/phy-meson-gxl-usb2.c
> 
> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
> index e8eb7f225a88..7d64711a837f 100644
> --- a/drivers/phy/Kconfig
> +++ b/drivers/phy/Kconfig
> @@ -486,4 +486,17 @@ config PHY_MESON8B_USB2
>  	  and GXBB SoCs.
>  	  If unsure, say N.
>  
> +config PHY_MESON_GXL_USB
> +	tristate "Meson GXL and GXM USB2 PHY drivers"
> +	default ARCH_MESON
> +	depends on OF && (ARCH_MESON || COMPILE_TEST)
> +	depends on USB_SUPPORT
> +	select USB_COMMON
> +	select GENERIC_PHY
> +	select REGMAP_MMIO
> +	help
> +	  Enable this to support the Meson USB2 PHYs found in Meson
> +	  GXL and GXM SoCs.
> +	  If unsure, say N.
> +
>  endmenu
> diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
> index 65eb2f436a41..a3a2c7dd5c06 100644
> --- a/drivers/phy/Makefile
> +++ b/drivers/phy/Makefile
> @@ -59,3 +59,4 @@ obj-$(CONFIG_PHY_CYGNUS_PCIE)		+= phy-bcm-cygnus-pcie.o
>  obj-$(CONFIG_ARCH_TEGRA) += tegra/
>  obj-$(CONFIG_PHY_NS2_PCIE)		+= phy-bcm-ns2-pcie.o
>  obj-$(CONFIG_PHY_MESON8B_USB2)		+= phy-meson8b-usb2.o
> +obj-$(CONFIG_PHY_MESON_GXL_USB)		+= phy-meson-gxl-usb2.o
> diff --git a/drivers/phy/phy-meson-gxl-usb2.c b/drivers/phy/phy-meson-gxl-usb2.c
> new file mode 100644
> index 000000000000..841a6d9722d4
> --- /dev/null
> +++ b/drivers/phy/phy-meson-gxl-usb2.c
> @@ -0,0 +1,263 @@
> +/*
> + * Meson GXL and GXM USB2 PHY driver
> + *
> + * Copyright (C) 2017 Martin Blumenstingl <martin.blumenstingl@googlemail.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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/regmap.h>
> +#include <linux/phy/phy.h>
> +#include <linux/platform_device.h>
> +#include <linux/usb/of.h>
> +
> +/* bits [31:27] are read-only */
> +#define U2P_R0							0x0
> +	#define U2P_R0_BYPASS_SEL				BIT(0)
> +	#define U2P_R0_BYPASS_DM_EN				BIT(1)
> +	#define U2P_R0_BYPASS_DP_EN				BIT(2)
> +	#define U2P_R0_TXBITSTUFF_ENH				BIT(3)
> +	#define U2P_R0_TXBITSTUFF_EN				BIT(4)
> +	#define U2P_R0_DM_PULLDOWN				BIT(5)
> +	#define U2P_R0_DP_PULLDOWN				BIT(6)
> +	#define U2P_R0_DP_VBUS_VLD_EXT_SEL			BIT(7)
> +	#define U2P_R0_DP_VBUS_VLD_EXT				BIT(8)
> +	#define U2P_R0_ADP_PRB_EN				BIT(9)
> +	#define U2P_R0_ADP_DISCHARGE				BIT(10)
> +	#define U2P_R0_ADP_CHARGE				BIT(11)
> +	#define U2P_R0_DRV_VBUS					BIT(12)
> +	#define U2P_R0_ID_PULLUP				BIT(13)
> +	#define U2P_R0_LOOPBACK_EN_B				BIT(14)
> +	#define U2P_R0_OTG_DISABLE				BIT(15)
> +	#define U2P_R0_COMMON_ONN				BIT(16)
> +	#define U2P_R0_FSEL_MASK				GENMASK(19, 17)
> +	#define U2P_R0_REF_CLK_SEL_MASK				GENMASK(21, 20)
> +	#define U2P_R0_POWER_ON_RESET				BIT(22)
> +	#define U2P_R0_V_ATE_TEST_EN_B_MASK			GENMASK(24, 23)
> +	#define U2P_R0_ID_SET_ID_DQ				BIT(25)
> +	#define U2P_R0_ATE_RESET				BIT(26)
> +	#define U2P_R0_FSV_MINUS				BIT(27)
> +	#define U2P_R0_FSV_PLUS					BIT(28)
> +	#define U2P_R0_BYPASS_DM_DATA				BIT(29)
> +	#define U2P_R0_BYPASS_DP_DATA				BIT(30)
> +
> +#define U2P_R1							0x4
> +	#define U2P_R1_BURN_IN_TEST				BIT(0)
> +	#define U2P_R1_ACA_ENABLE				BIT(1)
> +	#define U2P_R1_DCD_ENABLE				BIT(2)
> +	#define U2P_R1_VDAT_SRC_EN_B				BIT(3)
> +	#define U2P_R1_VDAT_DET_EN_B				BIT(4)
> +	#define U2P_R1_CHARGES_SEL				BIT(5)
> +	#define U2P_R1_TX_PREEMP_PULSE_TUNE			BIT(6)
> +	#define U2P_R1_TX_PREEMP_AMP_TUNE_MASK			GENMASK(8, 7)
> +	#define U2P_R1_TX_RES_TUNE_MASK				GENMASK(10, 9)
> +	#define U2P_R1_TX_RISE_TUNE_MASK			GENMASK(12, 11)
> +	#define U2P_R1_TX_VREF_TUNE_MASK			GENMASK(16, 13)
> +	#define U2P_R1_TX_FSLS_TUNE_MASK			GENMASK(20, 17)
> +	#define U2P_R1_TX_HSXV_TUNE_MASK			GENMASK(22, 21)
> +	#define U2P_R1_OTG_TUNE_MASK				GENMASK(25, 23)
> +	#define U2P_R1_SQRX_TUNE_MASK				GENMASK(28, 26)
> +	#define U2P_R1_COMP_DIS_TUNE_MASK			GENMASK(31, 29)
> +
> +/* bits [31:14] are read-only */
> +#define U2P_R2							0x8
> +	#define U2P_R2_DATA_IN_MASK				GENMASK(3, 0)
> +	#define U2P_R2_DATA_IN_EN_MASK				GENMASK(7, 4)
> +	#define U2P_R2_ADDR_MASK				GENMASK(11, 8)
> +	#define U2P_R2_DATA_OUT_SEL				BIT(12)
> +	#define U2P_R2_CLK					BIT(13)
> +	#define U2P_R2_DATA_OUT_MASK				GENMASK(17, 14)
> +	#define U2P_R2_ACA_PIN_RANGE_C				BIT(18)
> +	#define U2P_R2_ACA_PIN_RANGE_B				BIT(19)
> +	#define U2P_R2_ACA_PIN_RANGE_A				BIT(20)
> +	#define U2P_R2_ACA_PIN_GND				BIT(21)
> +	#define U2P_R2_ACA_PIN_FLOAT				BIT(22)
> +	#define U2P_R2_CHARGE_DETECT				BIT(23)
> +	#define U2P_R2_DEVICE_SESSION_VALID			BIT(24)
> +	#define U2P_R2_ADP_PROBE				BIT(25)
> +	#define U2P_R2_ADP_SENSE				BIT(26)
> +	#define U2P_R2_SESSION_END				BIT(27)
> +	#define U2P_R2_VBUS_VALID				BIT(28)
> +	#define U2P_R2_B_VALID					BIT(29)
> +	#define U2P_R2_A_VALID					BIT(30)
> +	#define U2P_R2_ID_DIG					BIT(31)
> +
> +#define U2P_R3							0xc
> +
> +#define RESET_COMPLETE_TIME				500
> +
> +struct phy_meson_gxl_usb2_priv {
> +	struct regmap		*regmap;
> +	enum phy_mode		mode;
> +	int			is_enabled;
> +};
> +
> +static const struct regmap_config phy_meson_gxl_usb2_regmap_conf = {
> +	.reg_bits = 8,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +	.max_register = U2P_R3,
> +};
> +
> +static int phy_meson_gxl_usb2_set_mode(struct phy *phy, enum phy_mode mode)
> +{
> +	struct phy_meson_gxl_usb2_priv *priv = phy_get_drvdata(phy);
> +
> +	switch (mode) {
> +	case PHY_MODE_USB_HOST:
> +	case PHY_MODE_USB_OTG:
> +		regmap_update_bits(priv->regmap, U2P_R0, U2P_R0_DM_PULLDOWN,
> +				   U2P_R0_DM_PULLDOWN);
> +		regmap_update_bits(priv->regmap, U2P_R0, U2P_R0_DP_PULLDOWN,
> +				   U2P_R0_DP_PULLDOWN);
> +		regmap_update_bits(priv->regmap, U2P_R0, U2P_R0_ID_PULLUP, 0);
> +		break;
> +
> +	case PHY_MODE_USB_DEVICE:
> +		regmap_update_bits(priv->regmap, U2P_R0, U2P_R0_DM_PULLDOWN,
> +				   0);
> +		regmap_update_bits(priv->regmap, U2P_R0, U2P_R0_DP_PULLDOWN,
> +				   0);
> +		regmap_update_bits(priv->regmap, U2P_R0, U2P_R0_ID_PULLUP,
> +				   U2P_R0_ID_PULLUP);
> +		break;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	if (priv->is_enabled) {
> +		/* reset the PHY and wait until settings are stabilized */
> +		regmap_update_bits(priv->regmap, U2P_R0, U2P_R0_POWER_ON_RESET,
> +				U2P_R0_POWER_ON_RESET);
> +		udelay(RESET_COMPLETE_TIME);
> +		regmap_update_bits(priv->regmap, U2P_R0, U2P_R0_POWER_ON_RESET,
> +				   0);
> +		udelay(RESET_COMPLETE_TIME);
> +	}
> +
> +	priv->mode = mode;
> +
> +	return 0;
> +}
> +
> +static int phy_meson_gxl_usb2_power_off(struct phy *phy)
> +{
> +	struct phy_meson_gxl_usb2_priv *priv = phy_get_drvdata(phy);
> +
> +	priv->is_enabled = 0;
> +
> +	/* power off the PHY by putting it into reset mode */
> +	regmap_update_bits(priv->regmap, U2P_R0, U2P_R0_POWER_ON_RESET,
> +			   U2P_R0_POWER_ON_RESET);
> +
> +	return 0;
> +}
> +
> +static int phy_meson_gxl_usb2_power_on(struct phy *phy)
> +{
> +	struct phy_meson_gxl_usb2_priv *priv = phy_get_drvdata(phy);
> +	int ret;
> +
> +	priv->is_enabled = 1;
> +
> +	/* power on the PHY by taking it out of reset mode */
> +	regmap_update_bits(priv->regmap, U2P_R0, U2P_R0_POWER_ON_RESET, 0);
> +
> +	ret = phy_meson_gxl_usb2_set_mode(phy, priv->mode);
> +	if (ret) {
> +		phy_meson_gxl_usb2_power_off(phy);
> +
> +		dev_err(&phy->dev, "Failed to initialize PHY with mode %d\n",
> +			priv->mode);
Shouldn't priv->is_enabled be reseted to 0 in this case?
> +		return ret;
> +	}
> +
> +	return 0;
This can be merged with return ret from the error case.
> +}
> +
> +static const struct phy_ops phy_meson_gxl_usb2_ops = {
> +	.power_on	= phy_meson_gxl_usb2_power_on,
> +	.power_off	= phy_meson_gxl_usb2_power_off,
> +	.set_mode	= phy_meson_gxl_usb2_set_mode,
> +	.owner		= THIS_MODULE,
> +};
> +
> +static int phy_meson_gxl_usb2_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct phy_provider *phy_provider;
> +	struct resource *res;
> +	struct phy_meson_gxl_usb2_priv *priv;
> +	struct phy *phy;
> +	void __iomem *base;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	switch (of_usb_get_dr_mode_by_phy(dev->of_node, -1)) {
> +	case USB_DR_MODE_PERIPHERAL:
> +		priv->mode = PHY_MODE_USB_DEVICE;
> +		break;
> +	case USB_DR_MODE_OTG:
> +		priv->mode = PHY_MODE_USB_OTG;
> +		break;
> +	case USB_DR_MODE_HOST:
> +	default:
> +		priv->mode = PHY_MODE_USB_HOST;
> +		break;
> +	}
> +
> +	priv->regmap = devm_regmap_init_mmio(dev, base,
> +					     &phy_meson_gxl_usb2_regmap_conf);
> +	if (IS_ERR(priv->regmap))
> +		return PTR_ERR(priv->regmap);
> +
> +	phy = devm_phy_create(dev, NULL, &phy_meson_gxl_usb2_ops);
> +	if (IS_ERR(phy)) {
> +		dev_err(dev, "failed to create PHY\n");
> +		return PTR_ERR(phy);
> +	}
> +
> +	phy_set_drvdata(phy, priv);
> +
> +	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
> +
> +	return PTR_ERR_OR_ZERO(phy_provider);
> +}
> +
> +static const struct of_device_id phy_meson_gxl_usb2_of_match[] = {
> +	{ .compatible = "amlogic,meson-gxl-usb2-phy", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, phy_meson_gxl_usb2_of_match);
> +
> +static struct platform_driver phy_meson_gxl_usb2_driver = {
> +	.probe	= phy_meson_gxl_usb2_probe,
> +	.driver	= {
> +		.name		= "phy-meson-gxl-usb2",
> +		.of_match_table	= phy_meson_gxl_usb2_of_match,
> +	},
> +};
> +module_platform_driver(phy_meson_gxl_usb2_driver);
> +
> +MODULE_AUTHOR("Martin Blumenstingl <martin.blumenstingl@googlemail.com>");
> +MODULE_DESCRIPTION("Meson GXL and GXM USB2 PHY driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.12.0
> 
> 
> _______________________________________________
> linux-amlogic mailing list
> linux-amlogic@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-amlogic