git.openwrt.org Git - openwrt/staging/ldir.git/blob

   1 From 4b0c6453808a662869a43c504913f3b7ed64486a Mon Sep 17 00:00:00 2001
   2 From: Jonathan Bell <jonathan@raspberrypi.com>
   3 Date: Wed, 20 Sep 2023 13:01:11 +0100
   4 Subject: [PATCH] drivers: pci: brcmstb: optionally extend Tperst_clk time
   5  during link-up
   6
   7 The RC has a feature that allows for manual control over the deassertion
   8 of the PERST# output pin, which allows the time between refclk active
   9 and reset deassert at the EP to be increased.
  10
  11 Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
  12 ---
  13  drivers/pci/controller/pcie-brcmstb.c | 24 +++++++++++++++++++++++-
  14  1 file changed, 23 insertions(+), 1 deletion(-)
  15
  16 --- a/drivers/pci/controller/pcie-brcmstb.c
  17 +++ b/drivers/pci/controller/pcie-brcmstb.c
  18 @@ -138,6 +138,7 @@
  19
  20  #define PCIE_MISC_HARD_PCIE_HARD_DEBUG pcie->reg_offsets[PCIE_HARD_DEBUG]
  21  #define  PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_DEBUG_ENABLE_MASK       0x2
  22 +#define  PCIE_MISC_HARD_PCIE_HARD_DEBUG_PERST_ASSERT_MASK              0x8
  23  #define  PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK               0x08000000
  24  #define  PCIE_BMIPS_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK         0x00800000
  25  #define  PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_L1SS_ENABLE_MASK                0x00200000
  26 @@ -352,6 +353,7 @@ struct brcm_pcie {
  27         bool                    (*rc_mode)(struct brcm_pcie *pcie);
  28         struct subdev_regulators *sr;
  29         bool                    ep_wakeup_capable;
  30 +       u32                     tperst_clk_ms;
  31  };
  32
  33  static inline bool is_bmips(const struct brcm_pcie *pcie)
  34 @@ -1388,9 +1390,28 @@ static int brcm_pcie_start_link(struct b
  35         u16 nlw, cls, lnksta;
  36         bool ssc_good = false;
  37         int ret, i;
  38 +       u32 tmp;
  39
  40         /* Unassert the fundamental reset */
  41 -       pcie->perst_set(pcie, 0);
  42 +       if (pcie->tperst_clk_ms) {
  43 +               /*
  44 +                * Increase Tperst_clk time by forcing PERST# output low while
  45 +                * the internal reset is released, so the PLL generates stable
  46 +                * refclk output further in advance of PERST# deassertion.
  47 +                */
  48 +               tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
  49 +               u32p_replace_bits(&tmp, 1, PCIE_MISC_HARD_PCIE_HARD_DEBUG_PERST_ASSERT_MASK);
  50 +               writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
  51 +
  52 +               pcie->perst_set(pcie, 0);
  53 +               msleep(pcie->tperst_clk_ms);
  54 +
  55 +               tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
  56 +               u32p_replace_bits(&tmp, 0, PCIE_MISC_HARD_PCIE_HARD_DEBUG_PERST_ASSERT_MASK);
  57 +               writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
  58 +       } else {
  59 +               pcie->perst_set(pcie, 0);
  60 +       }
  61
  62         /*
  63          * Wait for 100ms after PERST# deassertion; see PCIe CEM specification
  64 @@ -1923,6 +1944,7 @@ static int brcm_pcie_probe(struct platfo
  65         pcie->ssc = of_property_read_bool(np, "brcm,enable-ssc");
  66         pcie->l1ss = of_property_read_bool(np, "brcm,enable-l1ss");
  67         pcie->rcb_mps_mode = of_property_read_bool(np, "brcm,enable-mps-rcb");
  68 +       of_property_read_u32(np, "brcm,tperst-clk-ms", &pcie->tperst_clk_ms);
  69
  70         ret = clk_prepare_enable(pcie->clk);
  71         if (ret) {