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

[Fabio Estevam <festevam@gmail.com>]

On Thu, May 11, 2017 at 6:01 AM, Peter Senna Tschudin
<peter.senna@collabora.com> wrote:

> Thank you for working on this! Your patch worked for me, but I needed to
> add an "extern void imx_pcie_remove(void);" before calling the function,
> which probably means I'm missing something.

The extern should be added into a header file.

> After applying this patch to u-boot, u-boot can initialize PCI and
> 4.11.0-next-20170510 will boot. Without your patch 4.11.0-next-20170510
> do not boot if u-boot initialize the PCI bus.
>
> Thanks a lot!
>
> Here is the patch I'm using for our board:

Stefano,

The patches that Tim/Peter posted solve a kernel hang with kernel 4.11
on mx6q when U-Boot has PCI support.

Could you please take a look and let us know if there is a more
generic way to fix this issue, like fixing it for all mx6qdl boards
that have PCI support?

I understand that ideally the imx6 pci driver should be converted to
driver model and then we add the .remove hook, like Lucas did for
Barebox:
https://git.pengutronix.de/cgit/barebox/commit/?id=f1da98da2760c21487bbba8f7fb957c843a22896

While the imx pci driver is not converted to device model, would you
be willing to accept such per board patches for the time being?

Please advise.

Thanks

>
> diff --git a/board/ge/bx50v3/bx50v3.c b/board/ge/bx50v3/bx50v3.c
> index cb49b58..7e03082 100644
> --- a/board/ge/bx50v3/bx50v3.c
> +++ b/board/ge/bx50v3/bx50v3.c
> @@ -829,6 +829,7 @@ static void remove_ethaddr_env_var(int index)
>         setenv(env_var_name, NULL);
>  }
>
> +extern void imx_pcie_remove(void);
>  int last_stage_init(void) {
>         int i;
>
> @@ -838,6 +839,8 @@ int last_stage_init(void) {
>                 remove_ethaddr_env_var(i);
>         }
>
> +       imx_pcie_remove();
> +
>         return 0;
>  }
>
> 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)
>  {