[PATCH v2 3/6] bus: mhi: host: Add support for 64bit register reads and writes

Krishna Chaitanya Chundru
2026-04-11T08:12:22Z

Some mhi registers are of 64 bit size, instead of reading high value
and low value separately provide a new function op to read & write to
64 bit register.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
---
drivers/bus/mhi/host/main.c | 12 ++++++++++++
include/linux/mhi.h | 6 ++++++
2 files changed, 18 insertions(+)

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index b7a727b1a5d1f20b570c62707a991ec5b85bfec7..99917593e1da06f1dece7b5b0037c2485953410f 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -67,6 +67,18 @@ void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
mhi_cntrl->write_reg(mhi_cntrl, base + offset, val);
}

+static int __must_check mhi_read_reg64(struct mhi_controller *mhi_cntrl,
+ void __iomem *base, u32 offset, u64 *out)
+{
+ return mhi_cntrl->read_reg64(mhi_cntrl, base + offset, out);
+}
+
+static void __maybe_unused mhi_write_reg64(struct mhi_controller *mhi_cntrl, void __iomem *base,
+ u32 offset, u64 val)
+{
+ mhi_cntrl->write_reg64(mhi_cntrl, base + offset, val);
+}
+
int __must_check mhi_write_reg_field(struct mhi_controller *mhi_cntrl,
void __iomem *base, u32 offset, u32 mask,
u32 val)
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index f39c8ca7c251954f2d83c1227d206b600b88c75f..8e7257a9c907fb03571a86e29db5534f492678c7 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -376,6 +376,8 @@ struct mhi_timesync_info {
* @unmap_single: CB function to destroy TRE buffer
* @read_reg: Read a MHI register via the physical link (required)
* @write_reg: Write a MHI register via the physical link (required)
+ * @read_reg64: Read a 64 bit MHI register via the physical link (optional)
+ * @write_reg64: Write a 64 bit MHI register via the physical link (optional)
* @reset: Controller specific reset function (optional)
* @edl_trigger: CB function to trigger EDL mode (optional)
* @buffer_len: Bounce buffer length
@@ -462,6 +464,10 @@ struct mhi_controller {
u32 *out);
void (*write_reg)(struct mhi_controller *mhi_cntrl, void __iomem *addr,
u32 val);
+ int (*read_reg64)(struct mhi_controller *mhi_cntrl, void __iomem *addr,
+ u64 *out);
+ void (*write_reg64)(struct mhi_controller *mhi_cntrl, void __iomem *addr,
+ u64 val);
void (*reset)(struct mhi_controller *mhi_cntrl);
int (*edl_trigger)(struct mhi_controller *mhi_cntrl);

--
2.34.1