* [PATCH AUTOSEL 6.12 19/23] mmc: dw_mmc: add a quirk for accessing 64-bit FIFOs in two halves
[not found] <20250331145510.1705478-1-sashal@kernel.org>
@ 2025-03-31 14:55 ` Sasha Levin
0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2025-03-31 14:55 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Kaustabh Chakraborty, Ulf Hansson, Sasha Levin, jh80.chung,
linux-mmc
From: Kaustabh Chakraborty <kauschluss@disroot.org>
[ Upstream commit 57c0902f8bec51add5a1eb908d8b876592725d81 ]
In certain DW MMC implementations (such as in some Exynos7870
controllers), 64-bit read/write is not allowed from a 64-bit FIFO.
Add a quirk which facilitates accessing the 64-bit FIFO registers in two
32-bit halves.
Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Link: https://lore.kernel.org/r/20250219-exynos7870-mmc-v2-2-b4255a3e39ed@disroot.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/mmc/host/dw_mmc.c | 94 ++++++++++++++++++++++++++++++++++++++-
drivers/mmc/host/dw_mmc.h | 27 +++++++++++
2 files changed, 119 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index e9f6e4e622901..55158540c28cf 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -2579,6 +2579,91 @@ static void dw_mci_pull_data64(struct dw_mci *host, void *buf, int cnt)
}
}
+static void dw_mci_push_data64_32(struct dw_mci *host, void *buf, int cnt)
+{
+ struct mmc_data *data = host->data;
+ int init_cnt = cnt;
+
+ /* try and push anything in the part_buf */
+ if (unlikely(host->part_buf_count)) {
+ int len = dw_mci_push_part_bytes(host, buf, cnt);
+
+ buf += len;
+ cnt -= len;
+
+ if (host->part_buf_count == 8) {
+ mci_fifo_l_writeq(host->fifo_reg, host->part_buf);
+ host->part_buf_count = 0;
+ }
+ }
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+ if (unlikely((unsigned long)buf & 0x7)) {
+ while (cnt >= 8) {
+ u64 aligned_buf[16];
+ int len = min(cnt & -8, (int)sizeof(aligned_buf));
+ int items = len >> 3;
+ int i;
+ /* memcpy from input buffer into aligned buffer */
+ memcpy(aligned_buf, buf, len);
+ buf += len;
+ cnt -= len;
+ /* push data from aligned buffer into fifo */
+ for (i = 0; i < items; ++i)
+ mci_fifo_l_writeq(host->fifo_reg, aligned_buf[i]);
+ }
+ } else
+#endif
+ {
+ u64 *pdata = buf;
+
+ for (; cnt >= 8; cnt -= 8)
+ mci_fifo_l_writeq(host->fifo_reg, *pdata++);
+ buf = pdata;
+ }
+ /* put anything remaining in the part_buf */
+ if (cnt) {
+ dw_mci_set_part_bytes(host, buf, cnt);
+ /* Push data if we have reached the expected data length */
+ if ((data->bytes_xfered + init_cnt) ==
+ (data->blksz * data->blocks))
+ mci_fifo_l_writeq(host->fifo_reg, host->part_buf);
+ }
+}
+
+static void dw_mci_pull_data64_32(struct dw_mci *host, void *buf, int cnt)
+{
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+ if (unlikely((unsigned long)buf & 0x7)) {
+ while (cnt >= 8) {
+ /* pull data from fifo into aligned buffer */
+ u64 aligned_buf[16];
+ int len = min(cnt & -8, (int)sizeof(aligned_buf));
+ int items = len >> 3;
+ int i;
+
+ for (i = 0; i < items; ++i)
+ aligned_buf[i] = mci_fifo_l_readq(host->fifo_reg);
+
+ /* memcpy from aligned buffer into output buffer */
+ memcpy(buf, aligned_buf, len);
+ buf += len;
+ cnt -= len;
+ }
+ } else
+#endif
+ {
+ u64 *pdata = buf;
+
+ for (; cnt >= 8; cnt -= 8)
+ *pdata++ = mci_fifo_l_readq(host->fifo_reg);
+ buf = pdata;
+ }
+ if (cnt) {
+ host->part_buf = mci_fifo_l_readq(host->fifo_reg);
+ dw_mci_pull_final_bytes(host, buf, cnt);
+ }
+}
+
static void dw_mci_pull_data(struct dw_mci *host, void *buf, int cnt)
{
int len;
@@ -3379,8 +3464,13 @@ int dw_mci_probe(struct dw_mci *host)
width = 16;
host->data_shift = 1;
} else if (i == 2) {
- host->push_data = dw_mci_push_data64;
- host->pull_data = dw_mci_pull_data64;
+ if ((host->quirks & DW_MMC_QUIRK_FIFO64_32)) {
+ host->push_data = dw_mci_push_data64_32;
+ host->pull_data = dw_mci_pull_data64_32;
+ } else {
+ host->push_data = dw_mci_push_data64;
+ host->pull_data = dw_mci_pull_data64;
+ }
width = 64;
host->data_shift = 3;
} else {
diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
index 6447b916990dc..5463392dc8110 100644
--- a/drivers/mmc/host/dw_mmc.h
+++ b/drivers/mmc/host/dw_mmc.h
@@ -281,6 +281,8 @@ struct dw_mci_board {
/* Support for longer data read timeout */
#define DW_MMC_QUIRK_EXTENDED_TMOUT BIT(0)
+/* Force 32-bit access to the FIFO */
+#define DW_MMC_QUIRK_FIFO64_32 BIT(1)
#define DW_MMC_240A 0x240a
#define DW_MMC_280A 0x280a
@@ -472,6 +474,31 @@ struct dw_mci_board {
#define mci_fifo_writel(__value, __reg) __raw_writel(__reg, __value)
#define mci_fifo_writeq(__value, __reg) __raw_writeq(__reg, __value)
+/*
+ * Some dw_mmc devices have 64-bit FIFOs, but expect them to be
+ * accessed using two 32-bit accesses. If such controller is used
+ * with a 64-bit kernel, this has to be done explicitly.
+ */
+static inline u64 mci_fifo_l_readq(void __iomem *addr)
+{
+ u64 ans;
+ u32 proxy[2];
+
+ proxy[0] = mci_fifo_readl(addr);
+ proxy[1] = mci_fifo_readl(addr + 4);
+ memcpy(&ans, proxy, 8);
+ return ans;
+}
+
+static inline void mci_fifo_l_writeq(void __iomem *addr, u64 value)
+{
+ u32 proxy[2];
+
+ memcpy(proxy, &value, 8);
+ mci_fifo_writel(addr, proxy[0]);
+ mci_fifo_writel(addr + 4, proxy[1]);
+}
+
/* Register access macros */
#define mci_readl(dev, reg) \
readl_relaxed((dev)->regs + SDMMC_##reg)
--
2.39.5
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