On Fri, Mar 28, 2025 at 11:02:09AM +0800, Richard Zhu wrote:
> Add the cold reset toggle for i.MX95 PCIe to align PHY's power up sequency.
>
> Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
> ---
> drivers/pci/controller/dwc/pci-imx6.c | 42 +++++++++++++++++++++++++++
> 1 file changed, 42 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 57aa777231ae..6051b3b5928f 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -71,6 +71,9 @@
> #define IMX95_SID_MASK GENMASK(5, 0)
> #define IMX95_MAX_LUT 32
>
> +#define IMX95_PCIE_RST_CTRL 0x3010
> +#define IMX95_PCIE_COLD_RST BIT(0)
> +
> #define to_imx_pcie(x) dev_get_drvdata((x)->dev)
>
> enum imx_pcie_variants {
> @@ -773,6 +776,43 @@ static int imx7d_pcie_core_reset(struct imx_pcie *imx_pcie, bool assert)
> return 0;
> }
>
> +static int imx95_pcie_core_reset(struct imx_pcie *imx_pcie, bool assert)
> +{
> + u32 val;
> +
> + if (assert) {
> + /*
> + * From i.MX95 PCIe PHY perspective, the COLD reset toggle
> + * should be complete after power-up by the following sequence.
> + * > 10us(at power-up)
> + * > 10ns(warm reset)
> + * |<------------>|
> + * ______________
> + * phy_reset ____/ \________________
> + * ____________
> + * ref_clk_en_______________________/
> + * Toggle COLD reset aligned with this sequence for i.MX95 PCIe.
> + */
> + regmap_set_bits(imx_pcie->iomuxc_gpr, IMX95_PCIE_RST_CTRL,
> + IMX95_PCIE_COLD_RST);
> + /*
> + * To make sure delay enough time, do regmap_read_bypassed
> + * before udelay(). Since udelay() might not use MMIO, and cause
> + * delay time less than setting value.
> + */
> + regmap_read_bypassed(imx_pcie->iomuxc_gpr, IMX95_PCIE_RST_CTRL,
> + &val);
> + udelay(15);
> + regmap_clear_bits(imx_pcie->iomuxc_gpr, IMX95_PCIE_RST_CTRL,
> + IMX95_PCIE_COLD_RST);
> + regmap_read_bypassed(imx_pcie->iomuxc_gpr, IMX95_PCIE_RST_CTRL,
> + &val);
> + udelay(10);
> + }
> +
> + return 0;
> +}
> +
> static void imx_pcie_assert_core_reset(struct imx_pcie *imx_pcie)
> {
> reset_control_assert(imx_pcie->pciephy_reset);
> @@ -1762,6 +1802,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
> .ltssm_mask = IMX95_PCIE_LTSSM_EN,
> .mode_off[0] = IMX95_PE0_GEN_CTRL_1,
> .mode_mask[0] = IMX95_PCIE_DEVICE_TYPE,
> + .core_reset = imx95_pcie_core_reset,
> .init_phy = imx95_pcie_init_phy,
> },
> [IMX8MQ_EP] = {
> @@ -1815,6 +1856,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
> .mode_off[0] = IMX95_PE0_GEN_CTRL_1,
> .mode_mask[0] = IMX95_PCIE_DEVICE_TYPE,
> .init_phy = imx95_pcie_init_phy,
> + .core_reset = imx95_pcie_core_reset,
> .epc_features = &imx95_pcie_epc_features,
> .mode = DW_PCIE_EP_TYPE,
> },
> --
> 2.37.1
>
