target/linux/ath79/patches-4.14/0019-MIPS-ath79-get-PCIe-controller-out-of-reset.patch

   1 From 308c2ef9c4f1be2e1cee699042671eb973b51803 Mon Sep 17 00:00:00 2001
   2 From: Mathias Kresin <dev@kresin.me>
   3 Date: Tue, 6 Mar 2018 08:37:43 +0100
   4 Subject: [PATCH 19/27] MIPS: ath79: get PCIe controller out of reset
   5
   6 The ar724x pci driver expects the PCIe controller to be brought out of
   7 reset by the bootloader.
   8
   9 At least the AVM Fritz 300E bootloader doesn't take care of releasing
  10 the different PCIe controller related resets which causes an endless
  11 hang as soon as either the PCIE Reset register (0x180f0018) or the PCI
  12 Application Control register (0x180f0000) is read from.
  13
  14 Do the full "PCIE Root Complex Initialization Sequence" if the PCIe
  15 host controller is still in reset during probing.
  16
  17 The QCA u-boot sleeps 10ms after the PCIE Application Control bit is
  18 set to ready. It has been shown that 10ms might not be enough time if
  19 PCIe should be used right after setting the bit. During my tests it
  20 took up to 20ms till the link was up. Giving the link up to 100ms
  21 should work for all cases.
  22
  23 Signed-off-by: Mathias Kresin <dev@kresin.me>
  24 ---
  25  arch/mips/pci/pci-ar724x.c | 42 ++++++++++++++++++++++++++++++++++++++++++
  26  1 file changed, 42 insertions(+)
  27
  28 --- a/arch/mips/pci/pci-ar724x.c
  29 +++ b/arch/mips/pci/pci-ar724x.c
  30 @@ -12,14 +12,18 @@
  31  #include <linux/irq.h>
  32  #include <linux/pci.h>
  33  #include <linux/init.h>
  34 +#include <linux/delay.h>
  35  #include <linux/platform_device.h>
  36  #include <asm/mach-ath79/ath79.h>
  37  #include <asm/mach-ath79/ar71xx_regs.h>
  38
  39 +#define AR724X_PCI_REG_APP             0x00
  40  #define AR724X_PCI_REG_RESET           0x18
  41  #define AR724X_PCI_REG_INT_STATUS      0x4c
  42  #define AR724X_PCI_REG_INT_MASK                0x50
  43
  44 +#define AR724X_PCI_APP_LTSSM_ENABLE    BIT(0)
  45 +
  46  #define AR724X_PCI_RESET_LINK_UP       BIT(0)
  47
  48  #define AR724X_PCI_INT_DEV0            BIT(14)
  49 @@ -325,6 +329,37 @@ static void ar724x_pci_irq_init(struct a
  50                                          apc);
  51  }
  52
  53 +static void ar724x_pci_hw_init(struct ar724x_pci_controller *apc)
  54 +{
  55 +       u32 ppl, app;
  56 +       int wait = 0;
  57 +
  58 +       /* deassert PCIe host controller and PCIe PHY reset */
  59 +       ath79_device_reset_clear(AR724X_RESET_PCIE);
  60 +       ath79_device_reset_clear(AR724X_RESET_PCIE_PHY);
  61 +
  62 +       /* remove the reset of the PCIE PLL */
  63 +       ppl = ath79_pll_rr(AR724X_PLL_REG_PCIE_CONFIG);
  64 +       ppl &= ~AR724X_PLL_REG_PCIE_CONFIG_PPL_RESET;
  65 +       ath79_pll_wr(AR724X_PLL_REG_PCIE_CONFIG, ppl);
  66 +
  67 +       /* deassert bypass for the PCIE PLL */
  68 +       ppl = ath79_pll_rr(AR724X_PLL_REG_PCIE_CONFIG);
  69 +       ppl &= ~AR724X_PLL_REG_PCIE_CONFIG_PPL_BYPASS;
  70 +       ath79_pll_wr(AR724X_PLL_REG_PCIE_CONFIG, ppl);
  71 +
  72 +       /* set PCIE Application Control to ready */
  73 +       app = __raw_readl(apc->ctrl_base + AR724X_PCI_REG_APP);
  74 +       app |= AR724X_PCI_APP_LTSSM_ENABLE;
  75 +       __raw_writel(app, apc->ctrl_base + AR724X_PCI_REG_APP);
  76 +
  77 +       /* wait up to 100ms for PHY link up */
  78 +       do {
  79 +               mdelay(10);
  80 +               wait++;
  81 +       } while (wait < 10 && !ar724x_pci_check_link(apc));
  82 +}
  83 +
  84  static int ar724x_pci_probe(struct platform_device *pdev)
  85  {
  86         struct ar724x_pci_controller *apc;
  87 @@ -383,6 +418,13 @@ static int ar724x_pci_probe(struct platf
  88         apc->pci_controller.io_resource = &apc->io_res;
  89         apc->pci_controller.mem_resource = &apc->mem_res;
  90
  91 +       /*
  92 +        * Do the full PCIE Root Complex Initialization Sequence if the PCIe
  93 +        * host controller is in reset.
  94 +        */
  95 +       if (ath79_reset_rr(AR724X_RESET_REG_RESET_MODULE) & AR724X_RESET_PCIE)
  96 +               ar724x_pci_hw_init(apc);
  97 +
  98         apc->link_up = ar724x_pci_check_link(apc);
  99         if (!apc->link_up)
 100                 dev_warn(&pdev->dev, "PCIe link is down\n");