Subject: Re: [PATCH 3/9] phy: qcom-m31: Introduce qcom,m31 USB phy driver

From: Varadarajan Narayanan <[email-masked]>
Date: Thu, 15 Jun 2023 11:19:36 +0530

On Wed, Jun 07, 2023 at 01:54:23PM +0200, Konrad Dybcio wrote:
>
>
> On 7.06.2023 12:56, Varadarajan Narayanan wrote:
> > Add the M31 USB2 phy driver
> >
> > Signed-off-by: Varadarajan Narayanan <[email-masked]>
> > ---
> >  drivers/phy/qualcomm/phy-qcom-m31.c | 360 ++++++++++++++++++++++++++++++++++++
> >  1 file changed, 360 insertions(+)
> >  create mode 100644 drivers/phy/qualcomm/phy-qcom-m31.c
> >
> > diff --git a/drivers/phy/qualcomm/phy-qcom-m31.c b/drivers/phy/qualcomm/phy-qcom-m31.c
> > new file mode 100644
> > index 0000000..d29a91e
> > --- /dev/null
> > +++ b/drivers/phy/qualcomm/phy-qcom-m31.c
> > @@ -0,0 +1,360 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (c) 2014-2016, 2020, The Linux Foundation. All rights reserved.
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/kernel.h>
> > +#include <linux/err.h>
> > +#include <linux/slab.h>
> > +#include <linux/clk.h>
> > +#include <linux/delay.h>
> > +#include <linux/io.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/usb/phy.h>
> > +#include <linux/reset.h>
> > +#include <linux/of_device.h>
> Please sort these

Ok.

> > +
> > +enum clk_reset_action {
> > +	CLK_RESET_DEASSERT	= 0,
> > +	CLK_RESET_ASSERT	= 1
> > +};
> > +
> > +#define USB2PHY_PORT_POWERDOWN		0xA4
> > +#define POWER_UP			BIT(0)
> > +#define POWER_DOWN			0
> > +
> > +#define USB2PHY_PORT_UTMI_CTRL1	0x40
> > +
> > +#define USB2PHY_PORT_UTMI_CTRL2	0x44
> > +#define UTMI_ULPI_SEL			BIT(7)
> > +#define UTMI_TEST_MUX_SEL		BIT(6)
> > +
> > +#define HS_PHY_CTRL_REG			0x10
> > +#define UTMI_OTG_VBUS_VALID             BIT(20)
> > +#define SW_SESSVLD_SEL                  BIT(28)
> > +
> > +#define USB_PHY_CFG0			0x94
> > +#define USB_PHY_UTMI_CTRL5		0x50
> > +#define USB_PHY_FSEL_SEL		0xB8
> > +#define USB_PHY_HS_PHY_CTRL_COMMON0	0x54
> > +#define USB_PHY_REFCLK_CTRL		0xA0
> > +#define USB_PHY_HS_PHY_CTRL2		0x64
> > +#define USB_PHY_UTMI_CTRL0		0x3c
> > +#define USB2PHY_USB_PHY_M31_XCFGI_1	0xBC
> > +#define USB2PHY_USB_PHY_M31_XCFGI_4	0xC8
> > +#define USB2PHY_USB_PHY_M31_XCFGI_5	0xCC
> > +#define USB2PHY_USB_PHY_M31_XCFGI_11	0xE4
> Could you sort them address-wise?

Ok.

> > +
> > +#define USB2_0_TX_ENABLE		BIT(2)
> > +#define HSTX_SLEW_RATE_565PS		3
> > +#define PLL_CHARGING_PUMP_CURRENT_35UA	(3 << 3)
> > +#define ODT_VALUE_38_02_OHM		(3 << 6)
> > +#define ODT_VALUE_45_02_OHM		BIT(2)
> > +#define HSTX_PRE_EMPHASIS_LEVEL_0_55MA	(1)
> Weird mix of values, bits, bitfields.. perhaps BIT(n) and
> GENMASK() (+ FIELD_PREP) would be more suitable?

Ok.

> > +
> > +#define UTMI_PHY_OVERRIDE_EN		BIT(1)
> > +#define POR_EN				BIT(1)
> Please associate these with their registers, like

Ok.

> #define FOO_REG		0xf00
>  #define POR_EN		BIT(1)
>
> > +#define FREQ_SEL			BIT(0)
> > +#define COMMONONN			BIT(7)
> > +#define FSEL				BIT(4)
> > +#define RETENABLEN			BIT(3)
> > +#define USB2_SUSPEND_N_SEL		BIT(3)
> > +#define USB2_SUSPEND_N			BIT(2)
> > +#define USB2_UTMI_CLK_EN		BIT(1)
> > +#define CLKCORE				BIT(1)
> > +#define ATERESET			~BIT(0)
> > +#define FREQ_24MHZ			(5 << 4)
> > +#define XCFG_COARSE_TUNE_NUM		(2 << 0)
> > +#define XCFG_FINE_TUNE_NUM		(1 << 3)
> same comment

Ok.

> > +
> > +static void m31usb_write_readback(void *base, u32 offset,
> > +					const u32 mask, u32 val);
> We don't need this forward-definition, just move the function up.
>
> > +
> > +struct m31usb_phy {
> > +	struct usb_phy		phy;
> > +	void __iomem		*base;
> > +	void __iomem		*qscratch_base;
> > +
> > +	struct reset_control	*phy_reset;
> > +
> > +	bool			cable_connected;
> > +	bool			suspended;
> > +	bool			ulpi_mode;
> > +};
> > +
> > +static void m31usb_reset(struct m31usb_phy *qphy, u32 action)
> > +{
> > +	if (action == CLK_RESET_ASSERT)
> > +		reset_control_assert(qphy->phy_reset);
> > +	else
> > +		reset_control_deassert(qphy->phy_reset);
> > +	wmb(); /* ensure data is written to hw register */
> Please move the comment above the call.

This is used only once. Hence, will move it to the calling location itself.

> > +}
> > +
> > +static void m31usb_phy_enable_clock(struct m31usb_phy *qphy)
> > +{
> > +	/* Enable override ctrl */
> > +	writel(UTMI_PHY_OVERRIDE_EN, qphy->base + USB_PHY_CFG0);
> Some of the comments are missing a space before '*/'
>
> Also, please consider adding some newlines to logically split the
> actions.
>
> > +	/* Enable POR*/
> > +	writel(POR_EN, qphy->base + USB_PHY_UTMI_CTRL5);
> > +	udelay(15);
> > +	/* Configure frequency select value*/
> > +	writel(FREQ_SEL, qphy->base + USB_PHY_FSEL_SEL);
> > +	/* Configure refclk frequency */
> > +	writel(COMMONONN | FSEL | RETENABLEN,
> > +		qphy->base + USB_PHY_HS_PHY_CTRL_COMMON0);
> > +	/* select refclk source */
> > +	writel(CLKCORE, qphy->base + USB_PHY_REFCLK_CTRL);
> > +	/* select ATERESET*/
> > +	writel(POR_EN & ATERESET, qphy->base + USB_PHY_UTMI_CTRL5);
> > +	writel(USB2_SUSPEND_N_SEL | USB2_SUSPEND_N | USB2_UTMI_CLK_EN,
> > +		qphy->base + USB_PHY_HS_PHY_CTRL2);
> > +	writel(0x0, qphy->base + USB_PHY_UTMI_CTRL5);
> > +	writel(USB2_SUSPEND_N | USB2_UTMI_CLK_EN,
> > +		qphy->base + USB_PHY_HS_PHY_CTRL2);
> > +	/* Disable override ctrl */
> > +	writel(0x0, qphy->base + USB_PHY_CFG0);
> > +}
> > +
> > +static void ipq5332_m31usb_phy_enable_clock(struct m31usb_phy *qphy)
> > +{
> > +	/* Enable override ctrl */
> > +	writel(UTMI_PHY_OVERRIDE_EN, qphy->base + USB_PHY_CFG0);
> > +	/* Enable POR*/
> ditto
>
> > +	writel(POR_EN, qphy->base + USB_PHY_UTMI_CTRL5);
> > +	udelay(15);
> > +	/* Configure frequency select value*/
> > +	writel(FREQ_SEL, qphy->base + USB_PHY_FSEL_SEL);
> > +	/* Configure refclk frequency */
> > +	writel(COMMONONN | FREQ_24MHZ | RETENABLEN,
> > +		qphy->base + USB_PHY_HS_PHY_CTRL_COMMON0);
> > +	/* select ATERESET*/
> > +	writel(POR_EN & ATERESET, qphy->base + USB_PHY_UTMI_CTRL5);
> > +	writel(USB2_SUSPEND_N_SEL | USB2_SUSPEND_N | USB2_UTMI_CLK_EN,
> > +		qphy->base + USB_PHY_HS_PHY_CTRL2);
> > +	writel(XCFG_COARSE_TUNE_NUM  | XCFG_FINE_TUNE_NUM,
> > +				qphy->base + USB2PHY_USB_PHY_M31_XCFGI_11);
> > +	/* Adjust HSTX slew rate to 565 ps*/
> > +	/* Adjust PLL lock Time counter for release clock to 35uA */
> > +	/* Adjust Manual control ODT value to 38.02 Ohm */
> > +	writel(HSTX_SLEW_RATE_565PS | PLL_CHARGING_PUMP_CURRENT_35UA |
> > +		ODT_VALUE_38_02_OHM, qphy->base + USB2PHY_USB_PHY_M31_XCFGI_4);
> These functions seem very similar, with the main difference being that
> IPQ5332 adds some more writes at the end. Perhaps some commonizing could
> be done?
>
> > +	/*
> > +	 * Enable to always turn on USB 2.0 TX driver
> > +	 * when system is in USB 2.0 HS mode
> > +	 */
> > +	writel(USB2_0_TX_ENABLE, qphy->base + USB2PHY_USB_PHY_M31_XCFGI_1);
> > +	/* Adjust Manual control ODT value to 45.02 Ohm */
> > +	/* Adjust HSTX Pre-emphasis level to 0.55mA */
> > +	writel(ODT_VALUE_45_02_OHM | HSTX_PRE_EMPHASIS_LEVEL_0_55MA,
> > +		qphy->base + USB2PHY_USB_PHY_M31_XCFGI_5);
> > +	udelay(4);
> > +	writel(0x0, qphy->base + USB_PHY_UTMI_CTRL5);
> > +	writel(USB2_SUSPEND_N | USB2_UTMI_CLK_EN,
> > +		qphy->base + USB_PHY_HS_PHY_CTRL2);
> > +}

Will change the above to table based register init, based on
compatible/data.

> > +
> > +static int m31usb_phy_init(struct usb_phy *phy)
> > +{
> > +	struct m31usb_phy *qphy = container_of(phy, struct m31usb_phy, phy);
> > +
> > +	/* Perform phy reset */
> > +	m31usb_reset(qphy, CLK_RESET_ASSERT);
> > +	usleep_range(1, 5);
> https://www.kernel.org/doc/Documentation/timers/timers-howto.txt
>
> this may not work as intended

Will change it to udelay(5).

> > +	m31usb_reset(qphy, CLK_RESET_DEASSERT);
> > +
> > +	/* configure for ULPI mode if requested */
> > +	if (qphy->ulpi_mode)
> > +		writel_relaxed(0x0, qphy->base + USB2PHY_PORT_UTMI_CTRL2);
> > +
> > +	/* Enable the PHY */
> > +	writel_relaxed(POWER_UP, qphy->base + USB2PHY_PORT_POWERDOWN);
> > +
> > +	/* Make sure above write completed */
> > +	wmb();
> As you're calling wmb in the reset func, dropping _relaxed from the
> ULPI and PORT_POWERDOWN writes should work the same

Ok.

> > +
> > +	/* Turn on phy ref clock*/
> > +	if (of_device_is_compatible(phy->dev->of_node,
> > +					"qcom,ipq5332-m31-usb-hsphy"))
> > +		ipq5332_m31usb_phy_enable_clock(qphy);
> > +	else
> > +		m31usb_phy_enable_clock(qphy);
> This should be done using OF match data.

Ok.

> > +
> > +	/* Set OTG VBUS Valid from HSPHY to controller */
> > +	m31usb_write_readback(qphy->qscratch_base, HS_PHY_CTRL_REG,
> > +				UTMI_OTG_VBUS_VALID, UTMI_OTG_VBUS_VALID);
> > +	/* Indicate value is driven by UTMI_OTG_VBUS_VALID bit */
> > +	m31usb_write_readback(qphy->qscratch_base, HS_PHY_CTRL_REG,
> > +				SW_SESSVLD_SEL, SW_SESSVLD_SEL);
> > +
> > +	return 0;
> > +}
> > +
> > +static void m31usb_phy_shutdown(struct usb_phy *phy)
> > +{
> > +	struct m31usb_phy *qphy = container_of(phy, struct m31usb_phy, phy);
> > +
> > +	/* Disable the PHY */
> > +	writel_relaxed(POWER_DOWN, qphy->base + USB2PHY_PORT_POWERDOWN);
> > +	/* Make sure above write completed */
> > +	wmb();
> > +}
> > +
> > +static void m31usb_write_readback(void *base, u32 offset,
> > +					const u32 mask, u32 val)
> The indentation here makes `const u32..` misaligned.
>
> > +{
> > +	u32 write_val, tmp = readl_relaxed(base + offset);
> > +
> > +	tmp &= ~mask; /* retain other bits */
> > +	write_val = tmp | val;
> > +
> > +	writel_relaxed(write_val, base + offset);
> > +	/* Make sure above write completed */
> > +	wmb();
> > +
> > +	/* Read back to see if val was written */
> > +	tmp = readl_relaxed(base + offset);
> > +	tmp &= mask; /* clear other bits */
> > +
> > +	if (tmp != val)
> > +		pr_err("%s: write: %x to QSCRATCH: %x FAILED\n",
> > +			__func__, val, offset);
> > +}
> > +
> > +static int m31usb_phy_notify_connect(struct usb_phy *phy,
> > +					enum usb_device_speed speed)
> > +{
> > +	struct m31usb_phy *qphy = container_of(phy, struct m31usb_phy, phy);
> > +
> > +	qphy->cable_connected = true;
> > +
> > +	dev_dbg(phy->dev, " cable_connected=%d\n", qphy->cable_connected);
> spurious space at the beginning of the string
>
> > +
> > +	/* Set OTG VBUS Valid from HSPHY to controller */
> > +	m31usb_write_readback(qphy->qscratch_base, HS_PHY_CTRL_REG,
> > +				UTMI_OTG_VBUS_VALID,
> > +				UTMI_OTG_VBUS_VALID);
> Please align the lines with the previous opening bracket
>
> > +
> > +	/* Indicate value is driven by UTMI_OTG_VBUS_VALID bit */
> > +	m31usb_write_readback(qphy->qscratch_base, HS_PHY_CTRL_REG,
> > +				SW_SESSVLD_SEL, SW_SESSVLD_SEL);
> > +
> > +	dev_dbg(phy->dev, "M31USB2 phy connect notification\n");
> > +	return 0;
> > +}
> > +
> > +static int m31usb_phy_notify_disconnect(struct usb_phy *phy,
> > +					enum usb_device_speed speed)
> > +{
> > +	struct m31usb_phy *qphy = container_of(phy, struct m31usb_phy, phy);
> > +
> > +	qphy->cable_connected = false;
> > +
> > +	dev_dbg(phy->dev, " cable_connected=%d\n", qphy->cable_connected);
> > +
> > +	/* Set OTG VBUS Valid from HSPHY to controller */
> > +	m31usb_write_readback(qphy->qscratch_base, HS_PHY_CTRL_REG,
> > +				UTMI_OTG_VBUS_VALID, 0);
> > +
> > +	/* Indicate value is driven by UTMI_OTG_VBUS_VALID bit */
> > +	m31usb_write_readback(qphy->qscratch_base, HS_PHY_CTRL_REG,
> > +				SW_SESSVLD_SEL, 0);
> > +
> > +	dev_dbg(phy->dev, "M31USB2 phy disconnect notification\n");
> > +	return 0;
> > +}

Will remove these functions. They are accessing 'qscratch' area that
is part of the controller space. It doesn't belong in this driver.

> > +static int m31usb_phy_probe(struct platform_device *pdev)
> > +{
> > +	struct m31usb_phy *qphy;
> > +	struct device *dev = &pdev->dev;
> > +	struct resource *res;
> > +	int ret;
> > +	const char *phy_type;
> Please sort these in a reverse-Christmas-tree order.

ok.

> > +
> > +	qphy = devm_kzalloc(dev, sizeof(*qphy), GFP_KERNEL);
> > +	if (!qphy)
> > +		return -ENOMEM;
> > +
> > +	qphy->phy.dev = dev;
> > +
> > +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> > +							"m31usb_phy_base");
> > +	qphy->base = devm_ioremap_resource(dev, res);
> devm_platform_get_and_ioremap_resource?

ok.

> > +	if (IS_ERR(qphy->base))
> > +		return PTR_ERR(qphy->base);
> > +
> > +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> > +							"qscratch_base");
> > +	if (res) {
> Do we expect platforms without this register space?
>
> > +		qphy->qscratch_base = devm_ioremap(dev, res->start,
> > +							resource_size(res));
> > +		if (IS_ERR(qphy->qscratch_base)) {
> > +			dev_dbg(dev, "couldn't ioremap qscratch_base\n");
> > +			qphy->qscratch_base = NULL;
> > +		}
> > +	}

Will remove this qscratch code.

> > +	qphy->phy_reset = devm_reset_control_get(dev, "usb2_phy_reset");
> not _exclusive?

Ok.

> > +	if (IS_ERR(qphy->phy_reset))
> > +		return PTR_ERR(qphy->phy_reset);
> > +
> > +	qphy->ulpi_mode = false;
> > +	ret = of_property_read_string(dev->of_node, "phy_type", &phy_type);
> of_usb_get_phy_mode?

Ok.

> > +
> > +	if (!ret) {
> > +		if (!strcasecmp(phy_type, "ulpi"))
> > +			qphy->ulpi_mode = true;
> > +	} else {
> > +		dev_err(dev, "error reading phy_type property\n");
> > +		return ret;
> > +	}
> > +
> > +	platform_set_drvdata(pdev, qphy);
> > +
> > +	qphy->phy.label			= "qcom-m31usb-phy";
> > +	qphy->phy.init			= m31usb_phy_init;
> > +	qphy->phy.shutdown		= m31usb_phy_shutdown;
> > +	qphy->phy.type			= USB_PHY_TYPE_USB2;
> > +
> > +	if (qphy->qscratch_base) {
> > +		qphy->phy.notify_connect        = m31usb_phy_notify_connect;
> > +		qphy->phy.notify_disconnect     = m31usb_phy_notify_disconnect;
> > +	}
> > +
> > +	ret = usb_add_phy_dev(&qphy->phy);
> > +
> > +	return ret;
> > +}
> > +
> > +static int m31usb_phy_remove(struct platform_device *pdev)
> Please make this return void and pass it to .remove_new

Ok.

> > +{
> > +	struct m31usb_phy *qphy = platform_get_drvdata(pdev);
> > +
> > +	usb_remove_phy(&qphy->phy);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id m31usb_phy_id_table[] = {
> > +	{ .compatible = "qcom,m31-usb-hsphy",},
> > +	{ .compatible = "qcom,ipq5332-m31-usb-hsphy",},
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, m31usb_phy_id_table);
> > +
> > +static struct platform_driver m31usb_phy_driver = {
> > +	.probe		= m31usb_phy_probe,
> > +	.remove		= m31usb_phy_remove,
> > +	.driver = {
> > +		.name	= "qcom-m31usb-phy",
> > +		.of_match_table = of_match_ptr(m31usb_phy_id_table),
> of_match_ptr is unnecessary, this driver depends on OF.

Ok.

Thanks
Varada

> Konrad
> > +	},
> > +};
> > +
> > +module_platform_driver(m31usb_phy_driver);
> > +
> > +MODULE_DESCRIPTION("USB2 Qualcomm M31 HSPHY driver");
> > +MODULE_LICENSE("GPL");

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