[PATCH v11 4/9] mmc: cavium: Work-around hardware bug on cn6xxx and cnf7xxx

Jan Glauber
2017-02-06T13:41:37Z

Prevent data corruption on cn6xxx and cnf7xxx.
Due to an imperfection in the design of the MMC bus hardware,
the 2nd to last cache block of a DMA read must be locked into the L2
cache.

Signed-off-by: Jan Glauber <jglauber@cavium.com>
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Steven J. Hill <steven.hill@cavium.com>
---
arch/mips/cavium-octeon/Makefile | 1 +
arch/mips/cavium-octeon/octeon-mmc-l2c.c | 98 ++++++++++++++++++++++++++++++++
drivers/mmc/host/cavium-mmc.c | 5 ++
drivers/mmc/host/cavium-mmc.h | 5 ++
drivers/mmc/host/cavium-pltfm-octeon.c | 30 ++++++++++
5 files changed, 139 insertions(+)
create mode 100644 arch/mips/cavium-octeon/octeon-mmc-l2c.c

diff --git a/arch/mips/cavium-octeon/Makefile b/arch/mips/cavium-octeon/Makefile
index 2a59265..4e17617 100644
--- a/arch/mips/cavium-octeon/Makefile
+++ b/arch/mips/cavium-octeon/Makefile
@@ -18,3 +18,4 @@ obj-y += crypto/
obj-$(CONFIG_MTD) += flash_setup.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_OCTEON_ILM) += oct_ilm.o
+obj-$(CONFIG_MMC_CAVIUM_OCTEON) += octeon-mmc-l2c.o
diff --git a/arch/mips/cavium-octeon/octeon-mmc-l2c.c b/arch/mips/cavium-octeon/octeon-mmc-l2c.c
new file mode 100644
index 0000000..6aaaf73
--- /dev/null
+++ b/arch/mips/cavium-octeon/octeon-mmc-l2c.c
@@ -0,0 +1,98 @@
+/*
+ * Driver for MMC and SSD cards for Cavium OCTEON SOCs.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2012-2016 Cavium Inc.
+ */
+#include <linux/export.h>
+#include <asm/octeon/octeon.h>
+
+/*
+ * The functions below are used for the EMMC-17978 workaround.
+ *
+ * Due to an imperfection in the design of the MMC bus hardware,
+ * the 2nd to last cache block of a DMA read must be locked into the L2 Cache.
+ * Otherwise, data corruption may occur.
+ */
+
+static inline void *phys_to_ptr(u64 address)
+{
+ return (void *)(address | (1ull << 63)); /* XKPHYS */
+}
+
+/**
+ * Lock a single line into L2. The line is zeroed before locking
+ * to make sure no dram accesses are made.
+ *
+ * @addr Physical address to lock
+ */
+static void l2c_lock_line(u64 addr)
+{
+ char *addr_ptr = phys_to_ptr(addr);
+
+ asm volatile (
+ "cache 31, %[line]" /* Unlock the line */
+ :: [line] "m" (*addr_ptr));
+}
+
+/**
+ * Unlock a single line in the L2 cache.
+ *
+ * @addr Physical address to unlock
+ *
+ * Return Zero on success
+ */
+static void l2c_unlock_line(u64 addr)
+{
+ char *addr_ptr = phys_to_ptr(addr);
+
+ asm volatile (
+ "cache 23, %[line]" /* Unlock the line */
+ :: [line] "m" (*addr_ptr));
+}
+
+/**
+ * Locks a memory region in the L2 cache
+ *
+ * @start - start address to begin locking
+ * @len - length in bytes to lock
+ */
+void l2c_lock_mem_region(u64 start, u64 len)
+{
+ u64 end;
+
+ /* Round start/end to cache line boundaries */
+ end = ALIGN(start + len - 1, CVMX_CACHE_LINE_SIZE);
+ start = ALIGN(start, CVMX_CACHE_LINE_SIZE);
+
+ while (start <= end) {
+ l2c_lock_line(start);
+ start += CVMX_CACHE_LINE_SIZE;
+ }
+ asm volatile("sync");
+}
+EXPORT_SYMBOL_GPL(l2c_lock_mem_region);
+
+/**
+ * Unlock a memory region in the L2 cache
+ *
+ * @start - start address to unlock
+ * @len - length to unlock in bytes
+ */
+void l2c_unlock_mem_region(u64 start, u64 len)
+{
+ u64 end;
+
+ /* Round start/end to cache line boundaries */
+ end = ALIGN(start + len - 1, CVMX_CACHE_LINE_SIZE);
+ start = ALIGN(start, CVMX_CACHE_LINE_SIZE);
+
+ while (start <= end) {
+ l2c_unlock_line(start);
+ start += CVMX_CACHE_LINE_SIZE;
+ }
+}
+EXPORT_SYMBOL_GPL(l2c_unlock_mem_region);
diff --git a/drivers/mmc/host/cavium-mmc.c b/drivers/mmc/host/cavium-mmc.c
index 40aee08..e9e6f76 100644
--- a/drivers/mmc/host/cavium-mmc.c
+++ b/drivers/mmc/host/cavium-mmc.c
@@ -439,6 +439,8 @@ irqreturn_t cvm_mmc_interrupt(int irq, void *dev_id)
req->done(req);

no_req_done:
+ if (host->dmar_fixup_done)
+ host->dmar_fixup_done(host);
if (host_done)
host->release_bus(host);
out:
@@ -559,6 +561,9 @@ static void cvm_mmc_dma_request(struct mmc_host *mmc,
host->dma_active = true;
host->int_enable(host, emm_int.val);

+ if (host->dmar_fixup)
+ host->dmar_fixup(host, mrq->cmd, data, addr);
+
/*
* If we have a valid SD card in the slot, we set the response
* bit mask to check for CRC errors and timeouts only.
diff --git a/drivers/mmc/host/cavium-mmc.h b/drivers/mmc/host/cavium-mmc.h
index e900dd1..f350212 100644
--- a/drivers/mmc/host/cavium-mmc.h
+++ b/drivers/mmc/host/cavium-mmc.h
@@ -40,6 +40,7 @@ struct cvm_mmc_host {
void __iomem *base;
void __iomem *dma_base;
u64 emm_cfg;
+ u64 n_minus_one; /* OCTEON II workaround location */
int last_slot;
struct clk *clk;
int sys_freq;
@@ -55,6 +56,10 @@ struct cvm_mmc_host {
void (*acquire_bus)(struct cvm_mmc_host *);
void (*release_bus)(struct cvm_mmc_host *);
void (*int_enable)(struct cvm_mmc_host *, u64);
+ /* required on some MIPS models */
+ void (*dmar_fixup)(struct cvm_mmc_host *, struct mmc_command *,
+ struct mmc_data *, u64);
+ void (*dmar_fixup_done)(struct cvm_mmc_host *);
};

struct cvm_mmc_slot {
diff --git a/drivers/mmc/host/cavium-pltfm-octeon.c b/drivers/mmc/host/cavium-pltfm-octeon.c
index e2a1d1f..4fbc67e 100644
--- a/drivers/mmc/host/cavium-pltfm-octeon.c
+++ b/drivers/mmc/host/cavium-pltfm-octeon.c
@@ -18,6 +18,9 @@

#define CVMX_MIO_BOOT_CTL CVMX_ADD_IO_SEG(0x00011800000000D0ull)

+extern void l2c_lock_mem_region(u64 start, u64 len);
+extern void l2c_unlock_mem_region(u64 start, u64 len);
+
static void octeon_mmc_acquire_bus(struct cvm_mmc_host *host)
{
/* Switch the MMC controller onto the bus. */
@@ -36,6 +39,28 @@ static void octeon_mmc_int_enable(struct cvm_mmc_host *host, u64 val)
writeq(val, host->base + MIO_EMM_INT_EN);
}

+static void octeon_mmc_dmar_fixup(struct cvm_mmc_host *host,
+ struct mmc_command *cmd,
+ struct mmc_data *data,
+ u64 addr)
+{
+ if (cmd->opcode != MMC_WRITE_MULTIPLE_BLOCK)
+ return;
+ if (data->blksz * data->blocks <= 1024)
+ return;
+
+ host->n_minus_one = addr + (data->blksz * data->blocks) - 1024;
+ l2c_lock_mem_region(host->n_minus_one, 512);
+}
+
+static void octeon_mmc_dmar_fixup_done(struct cvm_mmc_host *host)
+{
+ if (!host->n_minus_one)
+ return;
+ l2c_unlock_mem_region(host->n_minus_one, 512);
+ host->n_minus_one = 0;
+}
+
static int octeon_mmc_probe(struct platform_device *pdev)
{
struct device_node *cn, *node = pdev->dev.of_node;
@@ -54,6 +79,11 @@ static int octeon_mmc_probe(struct platform_device *pdev)
host->acquire_bus = octeon_mmc_acquire_bus;
host->release_bus = octeon_mmc_release_bus;
host->int_enable = octeon_mmc_int_enable;
+ if (OCTEON_IS_MODEL(OCTEON_CN6XXX) ||
+ OCTEON_IS_MODEL(OCTEON_CNF7XXX)) {
+ host->dmar_fixup = octeon_mmc_dmar_fixup;
+ host->dmar_fixup_done = octeon_mmc_dmar_fixup_done;
+ }

host->sys_freq = octeon_get_io_clock_rate();

--
2.9.0.rc0.21.g7777322