Re: [PATCH 16/20] PCI: rockchip: switch to HWORD_UPDATE* macros

Bjorn Helgaas
2025-06-12T19:37:30Z

On Thu, Jun 12, 2025 at 08:56:18PM +0200, Nicolas Frattaroli wrote:
> The era of hand-rolled HIWORD_UPDATE macros is over, at least for those
> drivers that use constant masks.
>
> The Rockchip PCI driver, like many other Rockchip drivers, has its very
> own definition of HIWORD_UPDATE.
>
> Remove it, and replace its usage with either HWORD_UPDATE, or two new
> header local macros for setting/clearing a bit with the high mask, which
> use HWORD_UPDATE_CONST internally. In the process, ENCODE_LANES needed
> to be adjusted, as HWORD_UPDATE* shifts the value for us.
>
> That this is equivalent was verified by first making all HWORD_UPDATE
> instances HWORD_UPDATE_CONST, then doing a static_assert() comparing it
> to the old macro (and for those with parameters, static_asserting for
> the full range of possible values with the old encode macro).
>
> What we get out of this is compile time error checking to make sure the
> value actually fits in the mask, and that the mask fits in the register,
> and also generally less icky code that writes shifted values when it
> actually just meant to set and clear a handful of bits.
>
> Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>

Looks good to me. I assume you want to merge these via a non-PCI tree
since this depends on patch 01/20. PCI subject convention would
capitalize "Switch":

PCI: rockchip: Switch to HWORD_UPDATE* macros

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
> drivers/pci/controller/pcie-rockchip.h | 35 +++++++++++++++++-----------------
> 1 file changed, 18 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/pci/controller/pcie-rockchip.h b/drivers/pci/controller/pcie-rockchip.h
> index 5864a20323f21a004bfee4ac6d3a1328c4ab4d8a..5f2e45f062d94cd75983f7ad0c5b708e5b4cfb6f 100644
> --- a/drivers/pci/controller/pcie-rockchip.h
> +++ b/drivers/pci/controller/pcie-rockchip.h
> @@ -11,6 +11,7 @@
> #ifndef _PCIE_ROCKCHIP_H
> #define _PCIE_ROCKCHIP_H
>
> +#include <linux/bitfield.h>
> #include <linux/clk.h>
> #include <linux/kernel.h>
> #include <linux/pci.h>
> @@ -21,10 +22,10 @@
> * The upper 16 bits of PCIE_CLIENT_CONFIG are a write mask for the lower 16
> * bits. This allows atomic updates of the register without locking.
> */
> -#define HIWORD_UPDATE(mask, val) (((mask) << 16) | (val))
> -#define HIWORD_UPDATE_BIT(val) HIWORD_UPDATE(val, val)
> +#define HWORD_SET_BIT(val) (HWORD_UPDATE_CONST((val), 1))
> +#define HWORD_CLR_BIT(val) (HWORD_UPDATE_CONST((val), 0))
>
> -#define ENCODE_LANES(x) ((((x) >> 1) & 3) << 4)
> +#define ENCODE_LANES(x) ((((x) >> 1) & 3))
> #define MAX_LANE_NUM 4
> #define MAX_REGION_LIMIT 32
> #define MIN_EP_APERTURE 28
> @@ -32,21 +33,21 @@
>
> #define PCIE_CLIENT_BASE 0x0
> #define PCIE_CLIENT_CONFIG (PCIE_CLIENT_BASE + 0x00)
> -#define PCIE_CLIENT_CONF_ENABLE HIWORD_UPDATE_BIT(0x0001)
> -#define PCIE_CLIENT_CONF_DISABLE HIWORD_UPDATE(0x0001, 0)
> -#define PCIE_CLIENT_LINK_TRAIN_ENABLE HIWORD_UPDATE_BIT(0x0002)
> -#define PCIE_CLIENT_LINK_TRAIN_DISABLE HIWORD_UPDATE(0x0002, 0)
> -#define PCIE_CLIENT_ARI_ENABLE HIWORD_UPDATE_BIT(0x0008)
> -#define PCIE_CLIENT_CONF_LANE_NUM(x) HIWORD_UPDATE(0x0030, ENCODE_LANES(x))
> -#define PCIE_CLIENT_MODE_RC HIWORD_UPDATE_BIT(0x0040)
> -#define PCIE_CLIENT_MODE_EP HIWORD_UPDATE(0x0040, 0)
> -#define PCIE_CLIENT_GEN_SEL_1 HIWORD_UPDATE(0x0080, 0)
> -#define PCIE_CLIENT_GEN_SEL_2 HIWORD_UPDATE_BIT(0x0080)
> +#define PCIE_CLIENT_CONF_ENABLE HWORD_SET_BIT(0x0001)
> +#define PCIE_CLIENT_CONF_DISABLE HWORD_CLR_BIT(0x0001)
> +#define PCIE_CLIENT_LINK_TRAIN_ENABLE HWORD_SET_BIT(0x0002)
> +#define PCIE_CLIENT_LINK_TRAIN_DISABLE HWORD_CLR_BIT(0x0002)
> +#define PCIE_CLIENT_ARI_ENABLE HWORD_SET_BIT(0x0008)
> +#define PCIE_CLIENT_CONF_LANE_NUM(x) HWORD_UPDATE(0x0030, ENCODE_LANES(x))
> +#define PCIE_CLIENT_MODE_RC HWORD_SET_BIT(0x0040)
> +#define PCIE_CLIENT_MODE_EP HWORD_CLR_BIT(0x0040)
> +#define PCIE_CLIENT_GEN_SEL_1 HWORD_CLR_BIT(0x0080)
> +#define PCIE_CLIENT_GEN_SEL_2 HWORD_SET_BIT(0x0080)
> #define PCIE_CLIENT_LEGACY_INT_CTRL (PCIE_CLIENT_BASE + 0x0c)
> -#define PCIE_CLIENT_INT_IN_ASSERT HIWORD_UPDATE_BIT(0x0002)
> -#define PCIE_CLIENT_INT_IN_DEASSERT HIWORD_UPDATE(0x0002, 0)
> -#define PCIE_CLIENT_INT_PEND_ST_PEND HIWORD_UPDATE_BIT(0x0001)
> -#define PCIE_CLIENT_INT_PEND_ST_NORMAL HIWORD_UPDATE(0x0001, 0)
> +#define PCIE_CLIENT_INT_IN_ASSERT HWORD_SET_BIT(0x0002)
> +#define PCIE_CLIENT_INT_IN_DEASSERT HWORD_CLR_BIT(0x0002)
> +#define PCIE_CLIENT_INT_PEND_ST_PEND HWORD_SET_BIT(0x0001)
> +#define PCIE_CLIENT_INT_PEND_ST_NORMAL HWORD_CLR_BIT(0x0001)
> #define PCIE_CLIENT_SIDE_BAND_STATUS (PCIE_CLIENT_BASE + 0x20)
> #define PCIE_CLIENT_PHY_ST BIT(12)
> #define PCIE_CLIENT_DEBUG_OUT_0 (PCIE_CLIENT_BASE + 0x3c)
>
> --
> 2.49.0
>