For some devices, it is essential that controllers handle repeated start
correctly and do not replace it with a stop/start combination. This
addition helps to test that because it will only return a version string
if repeated start is done properly.
Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/i2c/slave-testunit-backend.rst | 38 ++++++++++++++++++++
drivers/i2c/i2c-slave-testunit.c | 25 +++++++++++--
2 files changed, 61 insertions(+), 2 deletions(-)
diff --git a/Documentation/i2c/slave-testunit-backend.rst b/Documentation/i2c/slave-testunit-backend.rst
index 37142a48ab35..a0335782d109 100644
--- a/Documentation/i2c/slave-testunit-backend.rst
+++ b/Documentation/i2c/slave-testunit-backend.rst
@@ -133,3 +133,41 @@ later)::
# i2ctransfer -y 0 w3@0x30 0x03 0x01 0x10 r?
0x10 0x0f 0x0e 0x0d 0x0c 0x0b 0x0a 0x09 0x08 0x07 0x06 0x05 0x04 0x03 0x02 0x01 0x00
+
+0x04 GET_VERSION_WITH_REP_START
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. list-table::
+ :header-rows: 1
+
+ * - CMD
+ - DATAL
+ - DATAH
+ - DELAY
+
+ * - 0x04
+ - currently unused
+ - currently unused
+ - leave out, partial command!
+
+Partial command. After sending this command, the testunit will reply to a read
+message with a NUL terminated version string based on UTS_RELEASE. The first
+character is always a 'v' and the length of the version string is at maximum
+128 bytes. However, it will only respond if the read message is connected to
+the write message via repeated start. If your controller driver handles
+repeated start correctly, this will work::
+
+ # i2ctransfer -y 0 w3@0x30 4 0 0 r128
+ 0x76 0x36 0x2e 0x31 0x31 0x2e 0x30 0x2d 0x72 0x63 0x31 0x2d 0x30 0x30 0x30 0x30 ...
+
+If you want to decode to ASCII right away::
+
+ # echo -e "$(i2ctransfer -y 0 w3@0x30 4 0 0 r128 | sed 's/0x\(..\) \?/\\x\1/g')"
+ v6.11.0-rc1-00009-gd37a1b4d3fd0
+
+STOP/START combinations between the two messages will *not* work because they
+are not equivalent to a REPEATED START. As an example, this returns just the
+default response::
+
+ # i2cset -y 0 0x30 4 0 0 i; i2cget -y 0 0x30
+ 0x01
diff --git a/drivers/i2c/i2c-slave-testunit.c b/drivers/i2c/i2c-slave-testunit.c
index be1d2e900aef..19296ff09930 100644
--- a/drivers/i2c/i2c-slave-testunit.c
+++ b/drivers/i2c/i2c-slave-testunit.c
@@ -6,6 +6,7 @@
* Copyright (C) 2020 by Renesas Electronics Corporation
*/
+#include <generated/utsrelease.h>
#include <linux/bitops.h>
#include <linux/i2c.h>
#include <linux/init.h>
@@ -15,11 +16,13 @@
#include <linux/workqueue.h> /* FIXME: is system_long_wq the best choice? */
#define TU_CUR_VERSION 0x01
+#define TU_VERSION_MAX_LENGTH 128
enum testunit_cmds {
TU_CMD_READ_BYTES = 1, /* save 0 for ABORT, RESET or similar */
TU_CMD_SMBUS_HOST_NOTIFY,
TU_CMD_SMBUS_BLOCK_PROC_CALL,
+ TU_CMD_GET_VERSION_WITH_REP_START,
TU_NUM_CMDS
};
@@ -39,10 +42,13 @@ struct testunit_data {
unsigned long flags;
u8 regs[TU_NUM_REGS];
u8 reg_idx;
+ u8 read_idx;
struct i2c_client *client;
struct delayed_work worker;
};
+static char tu_version_info[] = "v" UTS_RELEASE "\0";
+
static void i2c_slave_testunit_work(struct work_struct *work)
{
struct testunit_data *tu = container_of(work, struct testunit_data, worker.work);
@@ -91,6 +97,8 @@ static int i2c_slave_testunit_slave_cb(struct i2c_client *client,
struct testunit_data *tu = i2c_get_clientdata(client);
bool is_proc_call = tu->reg_idx == 3 && tu->regs[TU_REG_DATAL] == 1 &&
tu->regs[TU_REG_CMD] == TU_CMD_SMBUS_BLOCK_PROC_CALL;
+ bool is_get_version = tu->reg_idx == 3 &&
+ tu->regs[TU_REG_CMD] == TU_CMD_GET_VERSION_WITH_REP_START;
int ret = 0;
switch (event) {
@@ -100,6 +108,7 @@ static int i2c_slave_testunit_slave_cb(struct i2c_client *client,
memset(tu->regs, 0, TU_NUM_REGS);
tu->reg_idx = 0;
+ tu->read_idx = 0;
break;
case I2C_SLAVE_WRITE_RECEIVED:
@@ -136,12 +145,21 @@ static int i2c_slave_testunit_slave_cb(struct i2c_client *client,
break;
case I2C_SLAVE_READ_PROCESSED:
- if (is_proc_call && tu->regs[TU_REG_DATAH])
+ /* Advance until we reach the NUL character */
+ if (is_get_version && tu_version_info[tu->read_idx] != 0)
+ tu->read_idx++;
+ else if (is_proc_call && tu->regs[TU_REG_DATAH])
tu->regs[TU_REG_DATAH]--;
+
fallthrough;
case I2C_SLAVE_READ_REQUESTED:
- *val = is_proc_call ? tu->regs[TU_REG_DATAH] : TU_CUR_VERSION;
+ if (is_get_version)
+ *val = tu_version_info[tu->read_idx];
+ else if (is_proc_call)
+ *val = tu->regs[TU_REG_DATAH];
+ else
+ *val = TU_CUR_VERSION;
break;
}
@@ -160,6 +178,9 @@ static int i2c_slave_testunit_probe(struct i2c_client *client)
i2c_set_clientdata(client, tu);
INIT_DELAYED_WORK(&tu->worker, i2c_slave_testunit_work);
+ if (sizeof(tu_version_info) > TU_VERSION_MAX_LENGTH)
+ tu_version_info[TU_VERSION_MAX_LENGTH - 1] = 0;
+
return i2c_slave_register(client, i2c_slave_testunit_slave_cb);
};
--
2.43.0
