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Date: Mon, 18 Apr 2022 04:55:05 +0000
From: Hongxing Zhu <hongxing.zhu@....com>
To: Lucas Stach <l.stach@...gutronix.de>,
"p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
"lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
"robh@...nel.org" <robh@...nel.org>,
"shawnguo@...nel.org" <shawnguo@...nel.org>,
"vkoul@...nel.org" <vkoul@...nel.org>,
"alexander.stein@...tq-group.com" <alexander.stein@...tq-group.com>
CC: "linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"kernel@...gutronix.de" <kernel@...gutronix.de>,
dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH v2 3/7] phy: freescale: imx8m-pcie: Add iMX8MP PCIe PHY
support
> -----Original Message-----
> From: Lucas Stach <l.stach@...gutronix.de>
> Sent: 2022年4月15日 4:59
> To: Hongxing Zhu <hongxing.zhu@....com>; p.zabel@...gutronix.de;
> bhelgaas@...gle.com; lorenzo.pieralisi@....com; robh@...nel.org;
> shawnguo@...nel.org; vkoul@...nel.org; alexander.stein@...tq-group.com
> Cc: linux-phy@...ts.infradead.org; devicetree@...r.kernel.org;
> linux-pci@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
> linux-kernel@...r.kernel.org; kernel@...gutronix.de; dl-linux-imx
> <linux-imx@....com>
> Subject: Re: [PATCH v2 3/7] phy: freescale: imx8m-pcie: Add iMX8MP PCIe PHY
> support
>
> Am Montag, dem 07.03.2022 um 17:07 +0800 schrieb Richard Zhu:
> > Add the i.MX8MP PCIe PHY support
> >
> > Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> > ---
> > drivers/phy/freescale/phy-fsl-imx8m-pcie.c | 205
> > ++++++++++++++++-----
> > 1 file changed, 163 insertions(+), 42 deletions(-)
> >
> > diff --git a/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > b/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > index 04b1aafb29f4..3d01da4323a6 100644
> > --- a/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > +++ b/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > @@ -11,6 +11,8 @@
> > #include <linux/mfd/syscon.h>
> > #include <linux/mfd/syscon/imx7-iomuxc-gpr.h>
> > #include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_device.h>
> > #include <linux/phy/phy.h>
> > #include <linux/platform_device.h>
> > #include <linux/regmap.h>
> > @@ -30,12 +32,10 @@
> > #define IMX8MM_PCIE_PHY_CMN_REG065 0x194
> > #define ANA_AUX_RX_TERM (BIT(7) | BIT(4))
> > #define ANA_AUX_TX_LVL GENMASK(3, 0)
> > -#define IMX8MM_PCIE_PHY_CMN_REG75 0x1D4
> > -#define PCIE_PHY_CMN_REG75_PLL_DONE 0x3
> > +#define IMX8MM_PCIE_PHY_CMN_REG075 0x1D4
> > +#define ANA_PLL_DONE 0x3
>
> Why do you drop the register prefix from the name here?
To prevent the codes from exceeding the 80 columns and align with the other
bit definitions, drop the prefix and keep the bit definitions as short as
possible.
>
> > #define PCIE_PHY_TRSV_REG5 0x414
> > -#define PCIE_PHY_TRSV_REG5_GEN1_DEEMP 0x2D
> > #define PCIE_PHY_TRSV_REG6 0x418
> > -#define PCIE_PHY_TRSV_REG6_GEN2_DEEMP 0xF
> >
> > #define IMX8MM_GPR_PCIE_REF_CLK_SEL GENMASK(25, 24)
> > #define IMX8MM_GPR_PCIE_REF_CLK_PLL
> FIELD_PREP(IMX8MM_GPR_PCIE_REF_CLK_SEL, 0x3)
> > @@ -46,16 +46,43 @@
> > #define IMX8MM_GPR_PCIE_SSC_EN BIT(16)
> > #define IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE BIT(9)
> >
> > +#define IMX8MP_GPR_REG0 0x0
> > +#define IMX8MP_GPR_CLK_MOD_EN BIT(0)
> > +#define IMX8MP_GPR_PHY_APB_RST BIT(4)
> > +#define IMX8MP_GPR_PHY_INIT_RST BIT(5)
> > +#define IMX8MP_GPR_REG1 0x4
> > +#define IMX8MP_GPR_PM_EN_CORE_CLK BIT(0)
> > +#define IMX8MP_GPR_PLL_LOCK BIT(13)
> > +#define IMX8MP_GPR_REG2 0x8
> > +#define IMX8MP_GPR_P_PLL_MASK GENMASK(5, 0)
> > +#define IMX8MP_GPR_M_PLL_MASK GENMASK(15, 6)
> > +#define IMX8MP_GPR_S_PLL_MASK GENMASK(18, 16)
> > +#define IMX8MP_GPR_P_PLL (0xc << 0)
> > +#define IMX8MP_GPR_M_PLL (0x320 << 6)
> > +#define IMX8MP_GPR_S_PLL (0x4 << 16)
> > +#define IMX8MP_GPR_REG3 0xc
> > +#define IMX8MP_GPR_PLL_CKE BIT(17)
> > +#define IMX8MP_GPR_PLL_RST BIT(31)
> > +
> > +enum imx8_pcie_phy_type {
> > + IMX8MM,
> > + IMX8MP,
> > +};
> > +
> > struct imx8_pcie_phy {
> > void __iomem *base;
> > + struct device *dev;
> > struct clk *clk;
> > struct phy *phy;
> > + struct regmap *hsio_blk_ctrl;
> > struct regmap *iomuxc_gpr;
> > struct reset_control *reset;
> > + struct reset_control *perst;
> > u32 refclk_pad_mode;
> > u32 tx_deemph_gen1;
> > u32 tx_deemph_gen2;
> > bool clkreq_unused;
> > + enum imx8_pcie_phy_type variant;
> > };
> >
> > static int imx8_pcie_phy_init(struct phy *phy) @@ -67,6 +94,87 @@
> > static int imx8_pcie_phy_init(struct phy *phy)
> > reset_control_assert(imx8_phy->reset);
> >
> > pad_mode = imx8_phy->refclk_pad_mode;
> > + switch (imx8_phy->variant) {
> > + case IMX8MM:
> > + /* Tune PHY de-emphasis setting to pass PCIe compliance. */
> > + if (imx8_phy->tx_deemph_gen1)
> > + writel(imx8_phy->tx_deemph_gen1,
> > + imx8_phy->base + PCIE_PHY_TRSV_REG5);
> > + if (imx8_phy->tx_deemph_gen2)
> > + writel(imx8_phy->tx_deemph_gen2,
> > + imx8_phy->base + PCIE_PHY_TRSV_REG6);
> > + break;
> > + case IMX8MP:
> > + reset_control_assert(imx8_phy->perst);
>
> Could you tell us something more about this reset. What exactly is it resetting.
> Do we really need to assert it before starting the HSIO PLL?
Yes, this reset should be asserted, otherwise, the PCIe wouldn't work.
I'm asking more details of this reset bit from design team, and would update
later after I get the response.
> AFAICS the PLL should be pretty much independent of the PHY.
Agree.
>
> Do we need to enable this PLL when the PHY gets an external refclock? I
> couldn't test it yet, but I suspect that the HSIO PLL is only needed as an
> internal reference, when the i.MX8MP is the refclock source, either through
> the PHY pads or via a clkout from the PLL.
>
Refer to my experience, the HSIO PLL should be enabled firstly.
> > + /* Set P=12,M=800,S=4 and must set ICP=2'b01. */
> > + regmap_update_bits(imx8_phy->hsio_blk_ctrl, IMX8MP_GPR_REG2,
> > + IMX8MP_GPR_P_PLL_MASK |
> > + IMX8MP_GPR_M_PLL_MASK |
> > + IMX8MP_GPR_S_PLL_MASK,
> > + IMX8MP_GPR_P_PLL |
> > + IMX8MP_GPR_M_PLL |
> > + IMX8MP_GPR_S_PLL);
> > + /* wait greater than 1/F_FREF =1/2MHZ=0.5us */
> > + udelay(1);
> > +
> > + regmap_update_bits(imx8_phy->hsio_blk_ctrl, IMX8MP_GPR_REG3,
> > + IMX8MP_GPR_PLL_RST,
> > + IMX8MP_GPR_PLL_RST);
> > + udelay(10);
> > +
> > + /* Set 1 to pll_cke of GPR_REG3 */
> > + regmap_update_bits(imx8_phy->hsio_blk_ctrl, IMX8MP_GPR_REG3,
> > + IMX8MP_GPR_PLL_CKE,
> > + IMX8MP_GPR_PLL_CKE);
> > +
> > + /* Lock time should be greater than 300cycle=300*0.5us=150us */
> > + ret = regmap_read_poll_timeout(imx8_phy->hsio_blk_ctrl,
> > + IMX8MP_GPR_REG1, val,
> > + val & IMX8MP_GPR_PLL_LOCK,
> > + 10, 1000);
> > + if (ret) {
> > + dev_err(imx8_phy->dev, "PCIe PLL lock timeout\n");
> > + return ret;
> > + }
> > +
> > + /* pcie_clock_module_en */
> > + regmap_update_bits(imx8_phy->hsio_blk_ctrl, IMX8MP_GPR_REG0,
> > + IMX8MP_GPR_CLK_MOD_EN,
> > + IMX8MP_GPR_CLK_MOD_EN);
>
> You shouldn't need to touch this bit. The HSIO blk-ctrl already enables this bit
> when the PCIe power-domain is powered up.
Okay, got that.
>
> > + udelay(10);
> > +
> > + reset_control_deassert(imx8_phy->reset);
> > + reset_control_deassert(imx8_phy->perst);
> > +
> > + /* release pcie_phy_apb_reset and pcie_phy_init_resetn */
> > + regmap_update_bits(imx8_phy->hsio_blk_ctrl, IMX8MP_GPR_REG0,
> > + IMX8MP_GPR_PHY_APB_RST |
> > + IMX8MP_GPR_PHY_INIT_RST,
> > + IMX8MP_GPR_PHY_APB_RST |
> > + IMX8MP_GPR_PHY_INIT_RST);
>
> Not sure about those yet. We might want to toggle them via a virtual PD in the
> HSIO blk-ctrl.
Refer to my understand, these reset should be a part of power-up sequence of
the PHY. It's reasonable to toggle them via a PD.
>
> > + break;
> > + }
> > +
> > + if (pad_mode == IMX8_PCIE_REFCLK_PAD_INPUT) {
> > + /* Configure the pad as input */
> > + val = readl(imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG061);
> > + writel(val & ~ANA_PLL_CLK_OUT_TO_EXT_IO_EN,
> > + imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG061);
> > + } else if (pad_mode == IMX8_PCIE_REFCLK_PAD_OUTPUT) {
> > + /* Configure the PHY to output the refclock via pad */
> > + writel(ANA_PLL_CLK_OUT_TO_EXT_IO_EN,
> > + imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG061);
> > + writel(ANA_PLL_CLK_OUT_TO_EXT_IO_SEL,
> > + imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG062);
> > + writel(AUX_PLL_REFCLK_SEL_SYS_PLL,
> > + imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG063);
> > + val = ANA_AUX_RX_TX_SEL_TX | ANA_AUX_TX_TERM;
> > + writel(val | ANA_AUX_RX_TERM_GND_EN,
> > + imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG064);
> > + writel(ANA_AUX_RX_TERM | ANA_AUX_TX_LVL,
> > + imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG065);
> > + }
> > +
> > /* Set AUX_EN_OVERRIDE 1'b0, when the CLKREQ# isn't hooked */
> > regmap_update_bits(imx8_phy->iomuxc_gpr, IOMUXC_GPR14,
> > IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE, @@ -91,42
> +199,30 @@ static
> > int imx8_pcie_phy_init(struct phy *phy)
> > regmap_update_bits(imx8_phy->iomuxc_gpr, IOMUXC_GPR14,
> > IMX8MM_GPR_PCIE_CMN_RST,
> > IMX8MM_GPR_PCIE_CMN_RST);
> > - usleep_range(200, 500);
> >
> > - if (pad_mode == IMX8_PCIE_REFCLK_PAD_INPUT) {
> > - /* Configure the pad as input */
> > - val = readl(imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG061);
> > - writel(val & ~ANA_PLL_CLK_OUT_TO_EXT_IO_EN,
> > - imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG061);
> > - } else if (pad_mode == IMX8_PCIE_REFCLK_PAD_OUTPUT) {
> > - /* Configure the PHY to output the refclock via pad */
> > - writel(ANA_PLL_CLK_OUT_TO_EXT_IO_EN,
> > - imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG061);
> > - writel(ANA_PLL_CLK_OUT_TO_EXT_IO_SEL,
> > - imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG062);
> > - writel(AUX_PLL_REFCLK_SEL_SYS_PLL,
> > - imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG063);
> > - val = ANA_AUX_RX_TX_SEL_TX | ANA_AUX_TX_TERM;
> > - writel(val | ANA_AUX_RX_TERM_GND_EN,
> > - imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG064);
> > - writel(ANA_AUX_RX_TERM | ANA_AUX_TX_LVL,
> > - imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG065);
> > + switch (imx8_phy->variant) {
> > + case IMX8MM:
> > + reset_control_deassert(imx8_phy->reset);
> > + usleep_range(200, 500);
> > + break;
> > +
> > + case IMX8MP:
> > + /* wait for core_clk enabled */
> > + ret = regmap_read_poll_timeout(imx8_phy->hsio_blk_ctrl,
> > + IMX8MP_GPR_REG1, val,
> > + val & IMX8MP_GPR_PM_EN_CORE_CLK,
> > + 10, 20000);
> > + if (ret) {
> > + dev_err(imx8_phy->dev, "PCIe CORE CLK enable failed\n");
> > + return ret;
> > + }
> > +
> > + break;
> > }
> >
> > - /* Tune PHY de-emphasis setting to pass PCIe compliance. */
> > - if (imx8_phy->tx_deemph_gen1)
> > - writel(imx8_phy->tx_deemph_gen1,
> > - imx8_phy->base + PCIE_PHY_TRSV_REG5);
> > - if (imx8_phy->tx_deemph_gen2)
> > - writel(imx8_phy->tx_deemph_gen2,
> > - imx8_phy->base + PCIE_PHY_TRSV_REG6);
> > -
> > - reset_control_deassert(imx8_phy->reset);
> > -
> > /* Polling to check the phy is ready or not. */
> > - ret = readl_poll_timeout(imx8_phy->base +
> IMX8MM_PCIE_PHY_CMN_REG75,
> > - val, val == PCIE_PHY_CMN_REG75_PLL_DONE,
> > - 10, 20000);
> > + ret = readl_poll_timeout(imx8_phy->base +
> IMX8MM_PCIE_PHY_CMN_REG075,
> > + val, val == ANA_PLL_DONE, 10, 20000);
> > return ret;
> > }
> >
> > @@ -153,18 +249,33 @@ static const struct phy_ops imx8_pcie_phy_ops =
> {
> > .owner = THIS_MODULE,
> > };
> >
> > +static const struct of_device_id imx8_pcie_phy_of_match[] = {
> > + {.compatible = "fsl,imx8mm-pcie-phy", .data = (void *)IMX8MM},
> > + {.compatible = "fsl,imx8mp-pcie-phy", .data = (void *)IMX8MP},
> > + { },
> > +};
> > +MODULE_DEVICE_TABLE(of, imx8_pcie_phy_of_match);
> > +
> > static int imx8_pcie_phy_probe(struct platform_device *pdev) {
> > struct phy_provider *phy_provider;
> > struct device *dev = &pdev->dev;
> > + const struct of_device_id *of_id;
> > struct device_node *np = dev->of_node;
> > struct imx8_pcie_phy *imx8_phy;
> > struct resource *res;
> >
> > + of_id = of_match_device(imx8_pcie_phy_of_match, dev);
> > + if (!of_id)
> > + return -EINVAL;
> > +
> > imx8_phy = devm_kzalloc(dev, sizeof(*imx8_phy), GFP_KERNEL);
> > if (!imx8_phy)
> > return -ENOMEM;
> >
> > + imx8_phy->dev = dev;
> > + imx8_phy->variant = (enum imx8_pcie_phy_type)of_id->data;
> > +
> > /* get PHY refclk pad mode */
> > of_property_read_u32(np, "fsl,refclk-pad-mode",
> > &imx8_phy->refclk_pad_mode);
> > @@ -201,6 +312,22 @@ static int imx8_pcie_phy_probe(struct
> platform_device *pdev)
> > dev_err(dev, "Failed to get PCIEPHY reset control\n");
> > return PTR_ERR(imx8_phy->reset);
> > }
> > + if (imx8_phy->variant == IMX8MP) {
> > + /* Grab HSIO MIX config register range */
> > + imx8_phy->hsio_blk_ctrl =
> > +
> syscon_regmap_lookup_by_compatible("fsl,imx8mp-hsio-blk-ctrl");
> > + if (IS_ERR(imx8_phy->hsio_blk_ctrl)) {
> > + dev_err(dev, "unable to find hsio mix registers\n");
> > + return PTR_ERR(imx8_phy->hsio_blk_ctrl);
> > + }
> > +
> > + imx8_phy->perst =
> > + devm_reset_control_get_exclusive(dev, "perst");
> > + if (IS_ERR(imx8_phy->perst)) {
> > + dev_err(dev, "Failed to get PCIEPHY perst control\n");
> > + return PTR_ERR(imx8_phy->perst);
> > + }
> > + }
>
> I still hope that we can push all the HSIO blk-ctrl register access into the
> blk-ctrl driver, by adding the PLL as a clock there and maybe abstracting the
> PHY reset bits a virtual PD for the PHY, so we don't need this direct access in
> the PHY driver. Depends a bit on weather we are able to get the sequencing
> right when splitting things across multiple drivers.
Agree, thanks for your considerations.
Best Regards
Richard Zhu
>
> Regards,
> Lucas
>
> >
> > res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > imx8_phy->base = devm_ioremap_resource(dev, res); @@ -218,12 +345,6
> > @@ static int imx8_pcie_phy_probe(struct platform_device *pdev)
> > return PTR_ERR_OR_ZERO(phy_provider); }
> >
> > -static const struct of_device_id imx8_pcie_phy_of_match[] = {
> > - {.compatible = "fsl,imx8mm-pcie-phy",},
> > - { },
> > -};
> > -MODULE_DEVICE_TABLE(of, imx8_pcie_phy_of_match);
> > -
> > static struct platform_driver imx8_pcie_phy_driver = {
> > .probe = imx8_pcie_phy_probe,
> > .driver = {
>
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