Hi Andrew,
first sorry that it took so long. The reason here is that my original
plan was to add 256-byte support to RECV_LEN in the I2C core and enable
it on R-Car afterwards. Sadly, I never found the time to drive this
forward. So, all RECV_LEN things got stuck for a while :(
> This patch (adapted) was tested with v4.14, but due to lack of real
> hardware with SMBus block read operations support, using "simulation",
> that is manual analysis of data, read from plain I2C devices with
> SMBus block read request.
You could wire up two R-Car I2C instances, set up one as an I2C slave
handled by the I2C testunit and then use the other instance with
SMBUS_BLOCK_PROC_CALL which also needs RECV_LEN. Check
Documentation/i2c/slave-testunit-backend.rst for details.
I wonder a bit about the complexity of your patch. In my WIP-branch for
256-byte transfers, I have the following patch. It is only missing the
range check for the received byte, but that it easy to add. Do you see
anything else missing? If not, I prefer this simpler version because it
is less intrusive and the state machine is a bit fragile (due to HW
issues with old HW).
From: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Date: Sun, 2 Aug 2020 00:24:52 +0200
Subject: [PATCH] i2c: rcar: add support for I2C_M_RECV_LEN
Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-rcar.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 217def2d7cb4..e473f5c0a708 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -528,6 +528,7 @@ static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
static void rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr)
{
struct i2c_msg *msg = priv->msg;
+ bool recv_len_init = priv->pos == 0 && msg->flags & I2C_M_RECV_LEN;
/* FIXME: sometimes, unknown interrupt happened. Do nothing */
if (!(msr & MDR))
@@ -542,11 +543,13 @@ static void rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr)
} else if (priv->pos < msg->len) {
/* get received data */
msg->buf[priv->pos] = rcar_i2c_read(priv, ICRXTX);
+ if (recv_len_init)
+ msg->len += msg->buf[0];
priv->pos++;
}
/* If next received data is the _LAST_, go to new phase. */
- if (priv->pos + 1 == msg->len) {
+ if (priv->pos + 1 == msg->len && !recv_len_init) {
if (priv->flags & ID_LAST_MSG) {
rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
} else {
@@ -889,7 +892,7 @@ static u32 rcar_i2c_func(struct i2c_adapter *adap)
* I2C_M_IGNORE_NAK (automatically sends STOP after NAK)
*/
u32 func = I2C_FUNC_I2C | I2C_FUNC_SLAVE |
- (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+ (I2C_FUNC_SMBUS_EMUL_ALL & ~I2C_FUNC_SMBUS_QUICK);
if (priv->flags & ID_P_HOST_NOTIFY)
func |= I2C_FUNC_SMBUS_HOST_NOTIFY;
Happy hacking,
Wolfram
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