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net: dsa: xrs700x: Correctly address device over I2C

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On read, master should send 31 MSB of the register (only even values
are ever used), followed by a 1 to indicate read. Then, reading two
bytes, the device will output the register's value.

On write, master sends 31 MSB of the register, followed by a 0 to
indicate write, followed by two bytes containing the register value.

Flexibilis' documentation (version 1.3) specifies the opposite
polarity (#read/write), but the scope indicates that it is, in fact,
read/#write.

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: George McCollister <george.mccollister@gmail.com>
Link: https://lore.kernel.org/r/20210202191645.439-1-tobias@waldekranz.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Tobias Waldekranz 2021-02-02 20:16:45 +01:00 committed by Jakub Kicinski
parent b53014f079
commit add285bce3
1 changed files with 14 additions and 17 deletions
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31
drivers/net/dsa/xrs700x/xrs700x_i2c.c
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@ -10,33 +10,34 @@
#include "xrs700x.h"
#include "xrs700x_reg.h"
struct xrs700x_i2c_cmd {
__be32 reg;
__be16 val;
} __packed;
static int xrs700x_i2c_reg_read(void *context, unsigned int reg,
unsigned int *val)
{
struct device *dev = context;
struct i2c_client *i2c = to_i2c_client(dev);
unsigned char buf[4];
struct xrs700x_i2c_cmd cmd;
int ret;
buf[0] = reg >> 23 & 0xff;
buf[1] = reg >> 15 & 0xff;
buf[2] = reg >> 7 & 0xff;
buf[3] = (reg & 0x7f) << 1;
cmd.reg = cpu_to_be32(reg | 1);
ret = i2c_master_send(i2c, buf, sizeof(buf));
ret = i2c_master_send(i2c, (char *)&cmd.reg, sizeof(cmd.reg));
if (ret < 0) {
dev_err(dev, "xrs i2c_master_send returned %d\n", ret);
return ret;
}
ret = i2c_master_recv(i2c, buf, 2);
ret = i2c_master_recv(i2c, (char *)&cmd.val, sizeof(cmd.val));
if (ret < 0) {
dev_err(dev, "xrs i2c_master_recv returned %d\n", ret);
return ret;
}
*val = buf[0] << 8 | buf[1];
*val = be16_to_cpu(cmd.val);
return 0;
}
@ -45,17 +46,13 @@ static int xrs700x_i2c_reg_write(void *context, unsigned int reg,
{
struct device *dev = context;
struct i2c_client *i2c = to_i2c_client(dev);
unsigned char buf[6];
struct xrs700x_i2c_cmd cmd;
int ret;
buf[0] = reg >> 23 & 0xff;
buf[1] = reg >> 15 & 0xff;
buf[2] = reg >> 7 & 0xff;
buf[3] = (reg & 0x7f) << 1 | 1;
buf[4] = val >> 8 & 0xff;
buf[5] = val & 0xff;
cmd.reg = cpu_to_be32(reg);
cmd.val = cpu_to_be16(val);
ret = i2c_master_send(i2c, buf, sizeof(buf));
ret = i2c_master_send(i2c, (char *)&cmd, sizeof(cmd));
if (ret < 0) {
dev_err(dev, "xrs i2c_master_send returned %d\n", ret);
return ret;