[U-Boot] [PATCH] drivers: pci: imx: add imx_pcie_remove function

[Stefano Babic]

On 12/05/2017 21:58, Tim Harvey wrote:
> There is no dedicated reset signal wired up for the MX6QDL thus if the
> bootloader enables the link we need some special handling to get the core
> back into a state where it is safe to touch it for configuration.
> 
> While there has been some special handling in the Linux kernel to do this,
> it was removed in 4.11 thus we need to do it properly in the bootloader
> and therefore without this if you enable PCI in the bootloader you will hang
> while booting the 4.11 kernel.
> 
> This puts the PCIe controller back into a safe state for the kernel driver
> before launching the kernel.
> 
> Signed-off-by: Tim Harvey <tharvey at gateworks.com>
> ---
>  arch/arm/imx-common/cpu.c |  3 +++
>  drivers/pci/pcie_imx.c    | 38 ++++++++++++++++++++++++++++++++++++++
>  include/pci.h             |  4 ++++
>  3 files changed, 45 insertions(+)
> 
> diff --git a/arch/arm/imx-common/cpu.c b/arch/arm/imx-common/cpu.c
> index 40fe813..74bdd24 100644
> --- a/arch/arm/imx-common/cpu.c
> +++ b/arch/arm/imx-common/cpu.c
> @@ -275,6 +275,9 @@ u32 get_ahb_clk(void)
>  
>  void arch_preboot_os(void)
>  {
> +#if defined(CONFIG_PCIE_IMX)
> +	imx_pcie_remove();
> +#endif
>  #if defined(CONFIG_CMD_SATA)
>  	sata_stop();
>  #if defined(CONFIG_MX6)
> diff --git a/drivers/pci/pcie_imx.c b/drivers/pci/pcie_imx.c
> index 732d59d..eab0a2b 100644
> --- a/drivers/pci/pcie_imx.c
> +++ b/drivers/pci/pcie_imx.c
> @@ -42,6 +42,9 @@
>  
>  /* PCIe Port Logic registers (memory-mapped) */
>  #define PL_OFFSET 0x700
> +#define PCIE_PL_PFLR (PL_OFFSET + 0x08)
> +#define PCIE_PL_PFLR_LINK_STATE_MASK		(0x3f << 16)
> +#define PCIE_PL_PFLR_FORCE_LINK			(1 << 15)
>  #define PCIE_PHY_DEBUG_R0 (PL_OFFSET + 0x28)
>  #define PCIE_PHY_DEBUG_R1 (PL_OFFSET + 0x2c)
>  #define PCIE_PHY_DEBUG_R1_LINK_UP		(1 << 4)
> @@ -445,6 +448,36 @@ static int imx6_pcie_assert_core_reset(void)
>  	/* Power up PCIe PHY */
>  	setbits_le32(&gpc_regs->cntr, PCIE_PHY_PUP_REQ);
>  #else
> +	/*
> +	 * If the bootloader already enabled the link we need some special
> +	 * handling to get the core back into a state where it is safe to
> +	 * touch it for configuration.  As there is no dedicated reset signal
> +	 * wired up for MX6QDL, we need to manually force LTSSM into "detect"
> +	 * state before completely disabling LTSSM, which is a prerequisite
> +	 * for core configuration.
> +	 *
> +	 * If both LTSSM_ENABLE and REF_SSP_ENABLE are active we have a strong
> +	 * indication that the bootloader activated the link.
> +	 */
> +	if (is_mx6dq()) {
> +		u32 val, gpr1, gpr12;
> +
> +		gpr1 = readl(&iomuxc_regs->gpr[1]);
> +		gpr12 = readl(&iomuxc_regs->gpr[12]);
> +		if ((gpr1 & IOMUXC_GPR1_PCIE_REF_CLK_EN) &&
> +		    (gpr12 & IOMUXC_GPR12_PCIE_CTL_2)) {
> +			val = readl(MX6_DBI_ADDR + PCIE_PL_PFLR);
> +			val &= ~PCIE_PL_PFLR_LINK_STATE_MASK;
> +			val |= PCIE_PL_PFLR_FORCE_LINK;
> +
> +			imx_pcie_fix_dabt_handler(true);
> +			writel(val, MX6_DBI_ADDR + PCIE_PL_PFLR);
> +			imx_pcie_fix_dabt_handler(false);
> +
> +			gpr12 &= ~IOMUXC_GPR12_PCIE_CTL_2;
> +			writel(val, &iomuxc_regs->gpr[12]);
> +		}
> +	}
>  	setbits_le32(&iomuxc_regs->gpr[1], IOMUXC_GPR1_TEST_POWERDOWN);
>  	clrbits_le32(&iomuxc_regs->gpr[1], IOMUXC_GPR1_REF_SSP_EN);
>  #endif
> @@ -652,6 +685,11 @@ void imx_pcie_init(void)
>  	}
>  }
>  
> +void imx_pcie_remove(void)
> +{
> +	imx6_pcie_assert_core_reset();
> +}
> +
>  /* Probe function. */
>  void pci_init_board(void)
>  {
> diff --git a/include/pci.h b/include/pci.h
> index d3c955e..c8ef997 100644
> --- a/include/pci.h
> +++ b/include/pci.h
> @@ -754,6 +754,10 @@ int pci_last_busno(void);
>  extern void pci_mpc85xx_init (struct pci_controller *hose);
>  #endif
>  
> +#ifdef CONFIG_PCIE_IMX
> +extern void imx_pcie_remove(void);
> +#endif
> +
>  #if !defined(CONFIG_DM_PCI) || defined(CONFIG_DM_PCI_COMPAT)
>  /**
>   * pci_write_bar32() - Write the address of a BAR including control bits
> 

Ok, I see - now the question to Jagan. Tim has not time to move to DM,
and you propose yourself as volunteer (welcome !) to do this job. Of
course, I will not let things broken if move cannot be done, but I will
prefer to wait having a proper long time fix.

Best regards,
Stefano

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