[PATCH v2 1/3] misc: eeprom_93xx46: Remove hardcoded bit lengths

From: Emmanuel Gil Peyrot
Date: Sat Apr 24 2021 - 17:25:56 EST


This avoids using magic numbers based on the length of an address or a
command, while we only want to differentiate between 8-bit and 16-bit.

The driver was previously wrapping around the offset in the write
operation, this now returns -EINVAL instead (but should never happen in
the first place).

If two pointer indirections are too many, we could move the flags to the
main struct instead, but I doubt it’s going to make any sensible
difference on any hardware.

Signed-off-by: Emmanuel Gil Peyrot <linkmauve@xxxxxxxxxxxx>
---
drivers/misc/eeprom/eeprom_93xx46.c | 57 ++++++++++++++++-------------
1 file changed, 32 insertions(+), 25 deletions(-)

diff --git a/drivers/misc/eeprom/eeprom_93xx46.c b/drivers/misc/eeprom/eeprom_93xx46.c
index 80114f4c80ad..ffdb8e5a26e0 100644
--- a/drivers/misc/eeprom/eeprom_93xx46.c
+++ b/drivers/misc/eeprom/eeprom_93xx46.c
@@ -9,6 +9,7 @@
#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/kernel.h>
+#include <linux/log2.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
@@ -70,6 +71,7 @@ static int eeprom_93xx46_read(void *priv, unsigned int off,
struct eeprom_93xx46_dev *edev = priv;
char *buf = val;
int err = 0;
+ int bits;

if (unlikely(off >= edev->size))
return 0;
@@ -83,21 +85,21 @@ static int eeprom_93xx46_read(void *priv, unsigned int off,
if (edev->pdata->prepare)
edev->pdata->prepare(edev);

+ /* The opcode in front of the address is three bits. */
+ bits = edev->addrlen + 3;
+
while (count) {
struct spi_message m;
struct spi_transfer t[2] = { { 0 } };
u16 cmd_addr = OP_READ << edev->addrlen;
size_t nbytes = count;
- int bits;

- if (edev->addrlen == 7) {
- cmd_addr |= off & 0x7f;
- bits = 10;
+ if (edev->pdata->flags & EE_ADDR8) {
+ cmd_addr |= off;
if (has_quirk_single_word_read(edev))
nbytes = 1;
} else {
- cmd_addr |= (off >> 1) & 0x3f;
- bits = 9;
+ cmd_addr |= (off >> 1);
if (has_quirk_single_word_read(edev))
nbytes = 2;
}
@@ -152,14 +154,14 @@ static int eeprom_93xx46_ew(struct eeprom_93xx46_dev *edev, int is_on)
int bits, ret;
u16 cmd_addr;

+ /* The opcode in front of the address is three bits. */
+ bits = edev->addrlen + 3;
+
cmd_addr = OP_START << edev->addrlen;
- if (edev->addrlen == 7) {
+ if (edev->pdata->flags & EE_ADDR8)
cmd_addr |= (is_on ? ADDR_EWEN : ADDR_EWDS) << 1;
- bits = 10;
- } else {
+ else
cmd_addr |= (is_on ? ADDR_EWEN : ADDR_EWDS);
- bits = 9;
- }

if (has_quirk_instruction_length(edev)) {
cmd_addr <<= 2;
@@ -205,15 +207,19 @@ eeprom_93xx46_write_word(struct eeprom_93xx46_dev *edev,
int bits, data_len, ret;
u16 cmd_addr;

+ if (unlikely(off >= edev->size))
+ return -EINVAL;
+
+ /* The opcode in front of the address is three bits. */
+ bits = edev->addrlen + 3;
+
cmd_addr = OP_WRITE << edev->addrlen;

- if (edev->addrlen == 7) {
- cmd_addr |= off & 0x7f;
- bits = 10;
+ if (edev->pdata->flags & EE_ADDR8) {
+ cmd_addr |= off;
data_len = 1;
} else {
- cmd_addr |= (off >> 1) & 0x3f;
- bits = 9;
+ cmd_addr |= (off >> 1);
data_len = 2;
}

@@ -253,7 +259,7 @@ static int eeprom_93xx46_write(void *priv, unsigned int off,
return count;

/* only write even number of bytes on 16-bit devices */
- if (edev->addrlen == 6) {
+ if (edev->pdata->flags & EE_ADDR16) {
step = 2;
count &= ~1;
}
@@ -295,14 +301,14 @@ static int eeprom_93xx46_eral(struct eeprom_93xx46_dev *edev)
int bits, ret;
u16 cmd_addr;

+ /* The opcode in front of the address is three bits. */
+ bits = edev->addrlen + 3;
+
cmd_addr = OP_START << edev->addrlen;
- if (edev->addrlen == 7) {
+ if (edev->pdata->flags & EE_ADDR8)
cmd_addr |= ADDR_ERAL << 1;
- bits = 10;
- } else {
+ else
cmd_addr |= ADDR_ERAL;
- bits = 9;
- }

if (has_quirk_instruction_length(edev)) {
cmd_addr <<= 2;
@@ -455,10 +461,12 @@ static int eeprom_93xx46_probe(struct spi_device *spi)
if (!edev)
return -ENOMEM;

+ edev->size = 128;
+
if (pd->flags & EE_ADDR8)
- edev->addrlen = 7;
+ edev->addrlen = ilog2(edev->size);
else if (pd->flags & EE_ADDR16)
- edev->addrlen = 6;
+ edev->addrlen = ilog2(edev->size) - 1;
else {
dev_err(&spi->dev, "unspecified address type\n");
return -EINVAL;
@@ -469,7 +477,6 @@ static int eeprom_93xx46_probe(struct spi_device *spi)
edev->spi = spi;
edev->pdata = pd;

- edev->size = 128;
edev->nvmem_config.type = NVMEM_TYPE_EEPROM;
edev->nvmem_config.name = dev_name(&spi->dev);
edev->nvmem_config.dev = &spi->dev;
--
2.31.1