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

[Peter Senna Tschudin <peter.senna@collabora.com>]

On Fri, May 12, 2017 at 05:25:22PM -0300, Fabio Estevam wrote:
> Hi Tim,
> 
> On Fri, May 12, 2017 at 4:58 PM, Tim Harvey <tharvey@gateworks.com> 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@gateworks.com>
> 
> This looks good:
> 
> Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
> 
> Added Peter on Cc in case he could send his Tested-by tag.

I confirm this patch solves my issues. Thank you Tim!

Tested-by: Peter Senna Tschudin <peter.senna@collabora.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
> > --
> > 2.7.4
> >