[PATCH RFC 4/4] i2c: slave-eeprom: convert to using a pointer in i2c_device_id

Dmitry Torokhov
2023-08-14T21:54:14Z

Switch the driver to use newly added "data" pointer in i2c_device_id and
introduce struct eeprom_chip to describe chip's characteristics instead
of cramming it all into an unisigned long and then decipher.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
drivers/i2c/i2c-slave-eeprom.c | 99 ++++++++++++++++++++++++++++--------------
1 file changed, 66 insertions(+), 33 deletions(-)

diff --git a/drivers/i2c/i2c-slave-eeprom.c b/drivers/i2c/i2c-slave-eeprom.c
index 5946c0d0aef9..1d2340da5a70 100644
--- a/drivers/i2c/i2c-slave-eeprom.c
+++ b/drivers/i2c/i2c-slave-eeprom.c
@@ -16,32 +16,29 @@
* EEPROMs, though. We currently use the 8 bit as a valid address.
*/

-#include <linux/bitfield.h>
#include <linux/firmware.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/module.h>
-#include <linux/of.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/sysfs.h>

+struct eeprom_chip {
+ u16 address_mask;
+ u8 num_address_bytes;
+ bool read_only;
+};
+
struct eeprom_data {
+ const struct eeprom_chip *chip;
struct bin_attribute bin;
spinlock_t buffer_lock;
u16 buffer_idx;
- u16 address_mask;
- u8 num_address_bytes;
u8 idx_write_cnt;
- bool read_only;
u8 buffer[];
};

-#define I2C_SLAVE_BYTELEN GENMASK(15, 0)
-#define I2C_SLAVE_FLAG_ADDR16 BIT(16)
-#define I2C_SLAVE_FLAG_RO BIT(17)
-#define I2C_SLAVE_DEVICE_MAGIC(_len, _flags) ((_flags) | ((_len) - 1))
-
static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
enum i2c_slave_event event, u8 *val)
{
@@ -49,17 +46,15 @@ static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,

switch (event) {
case I2C_SLAVE_WRITE_RECEIVED:
- if (eeprom->idx_write_cnt < eeprom->num_address_bytes) {
+ if (eeprom->idx_write_cnt < eeprom->chip->num_address_bytes) {
if (eeprom->idx_write_cnt == 0)
eeprom->buffer_idx = 0;
eeprom->buffer_idx = *val | (eeprom->buffer_idx << 8);
eeprom->idx_write_cnt++;
- } else {
- if (!eeprom->read_only) {
- spin_lock(&eeprom->buffer_lock);
- eeprom->buffer[eeprom->buffer_idx++ & eeprom->address_mask] = *val;
- spin_unlock(&eeprom->buffer_lock);
- }
+ } else if (!eeprom->chip->read_only) {
+ spin_lock(&eeprom->buffer_lock);
+ eeprom->buffer[eeprom->buffer_idx++ & eeprom->chip->address_mask] = *val;
+ spin_unlock(&eeprom->buffer_lock);
}
break;

@@ -69,7 +64,7 @@ static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
fallthrough;
case I2C_SLAVE_READ_REQUESTED:
spin_lock(&eeprom->buffer_lock);
- *val = eeprom->buffer[eeprom->buffer_idx & eeprom->address_mask];
+ *val = eeprom->buffer[eeprom->buffer_idx & eeprom->chip->address_mask];
spin_unlock(&eeprom->buffer_lock);
/*
* Do not increment buffer_idx here, because we don't know if
@@ -142,19 +137,25 @@ static int i2c_slave_init_eeprom_data(struct eeprom_data *eeprom, struct i2c_cli

static int i2c_slave_eeprom_probe(struct i2c_client *client)
{
- const struct i2c_device_id *id = i2c_client_get_device_id(client);
+ const struct i2c_device_id *id;
+ const struct eeprom_chip *chip;
struct eeprom_data *eeprom;
int ret;
- unsigned int size = FIELD_GET(I2C_SLAVE_BYTELEN, id->driver_data) + 1;
- unsigned int flag_addr16 = FIELD_GET(I2C_SLAVE_FLAG_ADDR16, id->driver_data);
+ unsigned int size;
+
+ id = i2c_client_get_device_id(client);
+ if (!id)
+ return -EINVAL;
+
+ chip = id->data;
+ size = chip->address_mask + 1;

- eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL);
+ eeprom = devm_kzalloc(&client->dev, struct_size(eeprom, buffer, size),
+ GFP_KERNEL);
if (!eeprom)
return -ENOMEM;

- eeprom->num_address_bytes = flag_addr16 ? 2 : 1;
- eeprom->address_mask = size - 1;
- eeprom->read_only = FIELD_GET(I2C_SLAVE_FLAG_RO, id->driver_data);
+ eeprom->chip = chip;
spin_lock_init(&eeprom->buffer_lock);
i2c_set_clientdata(client, eeprom);

@@ -190,15 +191,47 @@ static void i2c_slave_eeprom_remove(struct i2c_client *client)
sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);
}

+static const struct eeprom_chip chip_24c02 = {
+ .address_mask = 2048 / 8 - 1, .num_address_bytes = 1,
+};
+
+static const struct eeprom_chip chip_24c02ro = {
+ .address_mask = 2048 / 8 - 1, .num_address_bytes = 1, .read_only = true,
+};
+
+static const struct eeprom_chip chip_24c32 = {
+ .address_mask = 32768 / 8 - 1, .num_address_bytes = 2,
+};
+
+static const struct eeprom_chip chip_24c32ro = {
+ .address_mask = 32768 / 8 - 1, .num_address_bytes = 2, .read_only = true,
+};
+
+static const struct eeprom_chip chip_24c64 = {
+ .address_mask = 65536 / 8 - 1, .num_address_bytes = 2,
+};
+
+static const struct eeprom_chip chip_24c64ro = {
+ .address_mask = 65536 / 8 - 1, .num_address_bytes = 2, .read_only = true,
+};
+
+static const struct eeprom_chip chip_24c512 = {
+ .address_mask = 524288 / 8 - 1, .num_address_bytes = 2,
+};
+
+static const struct eeprom_chip chip_24c512ro = {
+ .address_mask = 524288 / 8 - 1, .num_address_bytes = 2, .read_only = true,
+};
+
static const struct i2c_device_id i2c_slave_eeprom_id[] = {
- { "slave-24c02", I2C_SLAVE_DEVICE_MAGIC(2048 / 8, 0) },
- { "slave-24c02ro", I2C_SLAVE_DEVICE_MAGIC(2048 / 8, I2C_SLAVE_FLAG_RO) },
- { "slave-24c32", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16) },
- { "slave-24c32ro", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
- { "slave-24c64", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16) },
- { "slave-24c64ro", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
- { "slave-24c512", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16) },
- { "slave-24c512ro", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
+ { "slave-24c02", .data = &chip_24c02 },
+ { "slave-24c02ro", .data = &chip_24c02ro },
+ { "slave-24c32", .data = &chip_24c32 },
+ { "slave-24c32ro", .data = &chip_24c32ro },
+ { "slave-24c64", .data = &chip_24c64 },
+ { "slave-24c64ro", .data = &chip_24c64ro },
+ { "slave-24c512", .data = &chip_24c512 },
+ { "slave-24c512ro", .data = &chip_24c512ro },
{ }
};
MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);

--
2.41.0.694.ge786442a9b-goog