Re: [PATCH v1 4/4] PCI: brcmstb: Augment driver for MIPs SOCs

Bjorn Helgaas
2022-07-06T21:42:16Z

On Thu, Dec 09, 2021 at 03:47:25PM -0500, Jim Quinlan wrote:
> The current brcmstb driver works for Arm and Arm64. A few things are
> modified here for us to support MIPs as well.
>
> o There are four outbound range register groups and each directs a window
> of up to 128MB. Even though there are four 128MB DT "ranges" in the
> bmips PCIe DT node, these ranges are contiguous and are collapsed into
> a single range by the OF range parser. Now the driver assumes a single
> range -- for MIPs only -- and splits it back into 128MB sizes.
>
> o For bcm7425, the config space accesses must be 32-bit reads or
> writes. In addition, the 4k config space register array is missing
> and not used.
>
> o The registers for the upper 32-bits of the outbound window address do
> not exist.
>
> o Burst size must be set to 256 (this refers to an internal bus).
> ...

> @@ -118,6 +118,7 @@
> #define PCIE_MISC_HARD_PCIE_HARD_DEBUG 0x4204
> #define PCIE_MISC_HARD_PCIE_HARD_DEBUG_CLKREQ_DEBUG_ENABLE_MASK 0x2
> #define PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK 0x08000000
> +#define PCIE_BMIPS_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK 0x00800000

> @@ -883,7 +937,10 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
> pcie->bridge_sw_init_set(pcie, 0);
>
> tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
> - tmp &= ~PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK;
> + if (is_bmips(pcie))
> + tmp &= ~PCIE_BMIPS_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK;
> + else
> + tmp &= ~PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK;
> writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
> /* Wait for SerDes to be stable */
> usleep_range(100, 200);

brcm_pcie_resume() has similar code that updates
PCIE_MISC_HARD_PCIE_HARD_DEBUG [1]:

tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
u32p_replace_bits(&tmp, 0, PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK);
writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);

/* wait for serdes to be stable */
udelay(100);

This patch didn't change brcm_pcie_resume() to check is_bmips().
Should it?

If so, it would be nice to use the same method for updating the value
(either u32p_replace_bits or plain C bitops) in both places.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/pcie-brcmstb.c?id=v5.18#n1452