[PATCH v3 16/20] PCI: rockchip: Switch to FIELD_PREP_WM16* macros

Nicolas Frattaroli
2025-08-25T08:33:42Z

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 FIELD_PREP_WM16, or two new
header local macros for setting/clearing a bit with the high mask, which
use FIELD_PREP_WM16_CONST internally. In the process, ENCODE_LANES
needed to be adjusted, as FIELD_PREP_WM16* shifts the value for us.

That this is equivalent was verified by first making all FIELD_PREP_WM16
instances FIELD_PREP_WM16_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.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.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 72a2c045f6fe95cb43f01a2841a5ca0f597c85d4..3e82a69b9c006e52d134278651c5a420a1f195c2 100644
--- a/drivers/pci/controller/pcie-rockchip.h
+++ b/drivers/pci/controller/pcie-rockchip.h
@@ -12,6 +12,7 @@
#define _PCIE_ROCKCHIP_H

#include <linux/clk.h>
+#include <linux/hw_bitfield.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/pci-ecam.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) (FIELD_PREP_WM16_CONST((val), 1))
+#define HWORD_CLR_BIT(val) (FIELD_PREP_WM16_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) FIELD_PREP_WM16(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)

--
2.51.0