On 10/08/2021 08:35, Joakim Zhang wrote:
This patch intends to introduce "reverse-data" property at nvmem
provider side to reverse buffer.
For a case used from Ethernet driver, of_get_mac_address() may call
of_get_mac_addr_nvmem() to get MAC address from nvmem device. MAC address
programed in imx-ocopt is MSB first in lowest address, so need reverse
Is all the data stored in imx-ocopt reverse byte order?
or someone decided to change the order for only mac-address?
data then feedback to nvmem consumer. E.g. MAC address read from
imx-ocopt is 98:e2:06:9f:04:00, after reversed the data is
00:04:9f:06:e2:98.
Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
---
drivers/nvmem/core.c | 30 ++++++++++++++++++++++++++++++
include/linux/nvmem-provider.h | 2 ++
2 files changed, 32 insertions(+)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index b3bc30a04ed7..ccc2c5801c8e 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -55,6 +55,7 @@ struct nvmem_cell {
struct device_node *np;
struct nvmem_device *nvmem;
struct list_head node;
+ u32 flags;
This flag also needs to go in struct nvmem_cell_info too.
};
static DEFINE_MUTEX(nvmem_mutex);
@@ -92,6 +93,26 @@ static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
return -EINVAL;
}
+static int nvmem_buffer_reverse(void *bufaddr, int len)
+{
+ u8 *buf = (u8 *)bufaddr;
+ u8 *temp;
+ int i;
+
+ temp = kzalloc(len, GFP_KERNEL);
+ if (!temp)
+ return -ENOMEM;
+
+ memcpy(temp, buf, len);
+
+ for (i = 0; i < len; i++)
+ buf[i] = temp[len - i - 1];
+
You could possibly simplify this.
static void nvmem_buffer_reverse(u8 *buf, int len)
{
int i;
for (i = 0; i < len/2; i++)
swap(buf[i], buf[len - i - 1]);
}
+ kfree(temp);
+
+ return 0;
+}
+
static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
unsigned int offset, void *val,
size_t bytes, int write)
@@ -705,6 +726,9 @@ static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
cell->bytes = be32_to_cpup(addr);
cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
+ if (of_property_read_bool(child, "reverse-data"))
+ cell->flags |= NVMEM_FLAGS_REVERSE_DATA;
+
addr = of_get_property(child, "bits", &len);
if (addr && len == (2 * sizeof(u32))) {
cell->bit_offset = be32_to_cpup(addr++);
@@ -1398,6 +1422,12 @@ static int __nvmem_cell_read(struct nvmem_device *nvmem,
if (cell->bit_offset || cell->nbits)
nvmem_shift_read_buffer_in_place(cell, buf);
+ if (cell->flags & NVMEM_FLAGS_REVERSE_DATA) {
+ rc = nvmem_buffer_reverse(buf, cell->bytes);
+ if (rc < 0)
+ return rc;
+ }
+
if (len)
*len = cell->bytes;
diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
index 104505e9028f..364ac2a61b11 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -31,6 +31,8 @@ enum nvmem_type {
#define NVMEM_DEVID_NONE (-1)
#define NVMEM_DEVID_AUTO (-2)
+#define NVMEM_FLAGS_REVERSE_DATA BIT(0)
Maybe NVMEM_FLAGS_REVERSE_BYTE_ORDER and some kerneldoc would help new
users.
--srini
+
/**
* struct nvmem_keepout - NVMEM register keepout range.
*
