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i2c: smbus: use DMA safe buffers for emulated SMBus transactions

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For all block commands, try to allocate a DMA safe buffer and mark it
accordingly. Only use the stack, if the buffers cannot be allocated.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Wolfram Sang 2017-11-04 21:20:06 +01:00 committed by Wolfram Sang
parent ba98645c7d
commit 8a77821e74
1 changed files with 39 additions and 6 deletions
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45
drivers/i2c/i2c-core-smbus.c
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@ -18,6 +18,7 @@
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/i2c-smbus.h>
#include <linux/slab.h>
#define CREATE_TRACE_POINTS
#include <trace/events/smbus.h>
@ -291,6 +292,22 @@ s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
}
EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
static void i2c_smbus_try_get_dmabuf(struct i2c_msg *msg, u8 init_val)
{
bool is_read = msg->flags & I2C_M_RD;
unsigned char *dma_buf;
dma_buf = kzalloc(I2C_SMBUS_BLOCK_MAX + (is_read ? 2 : 3), GFP_KERNEL);
if (!dma_buf)
return;
msg->buf = dma_buf;
msg->flags |= I2C_M_DMA_SAFE;
if (init_val)
msg->buf[0] = init_val;
}
/* Simulate a SMBus command using the i2c protocol
No checking of parameters is done! */
static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
@ -368,6 +385,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
msg[1].flags |= I2C_M_RECV_LEN;
msg[1].len = 1; /* block length will be added by
the underlying bus driver */
i2c_smbus_try_get_dmabuf(&msg[1], 0);
} else {
msg[0].len = data->block[0] + 2;
if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
@ -376,8 +394,10 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
data->block[0]);
return -EINVAL;
}
i2c_smbus_try_get_dmabuf(&msg[0], command);
for (i = 1; i < msg[0].len; i++)
msgbuf0[i] = data->block[i-1];
msg[0].buf[i] = data->block[i - 1];
}
break;
case I2C_SMBUS_BLOCK_PROC_CALL:
@ -389,16 +409,21 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
data->block[0]);
return -EINVAL;
}
msg[0].len = data->block[0] + 2;
i2c_smbus_try_get_dmabuf(&msg[0], command);
for (i = 1; i < msg[0].len; i++)
msgbuf0[i] = data->block[i-1];
msg[0].buf[i] = data->block[i - 1];
msg[1].flags |= I2C_M_RECV_LEN;
msg[1].len = 1; /* block length will be added by
the underlying bus driver */
i2c_smbus_try_get_dmabuf(&msg[1], 0);
break;
case I2C_SMBUS_I2C_BLOCK_DATA:
if (read_write == I2C_SMBUS_READ) {
msg[1].len = data->block[0];
i2c_smbus_try_get_dmabuf(&msg[1], 0);
} else {
msg[0].len = data->block[0] + 1;
if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
@ -407,8 +432,10 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
data->block[0]);
return -EINVAL;
}
i2c_smbus_try_get_dmabuf(&msg[0], command);
for (i = 1; i <= data->block[0]; i++)
msgbuf0[i] = data->block[i];
msg[0].buf[i] = data->block[i];
}
break;
default:
@ -456,14 +483,20 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
break;
case I2C_SMBUS_I2C_BLOCK_DATA:
for (i = 0; i < data->block[0]; i++)
data->block[i+1] = msgbuf1[i];
data->block[i + 1] = msg[1].buf[i];
break;
case I2C_SMBUS_BLOCK_DATA:
case I2C_SMBUS_BLOCK_PROC_CALL:
for (i = 0; i < msgbuf1[0] + 1; i++)
data->block[i] = msgbuf1[i];
for (i = 0; i < msg[1].buf[0] + 1; i++)
data->block[i] = msg[1].buf[i];
break;
}
if (msg[0].flags & I2C_M_DMA_SAFE)
kfree(msg[0].buf);
if (msg[1].flags & I2C_M_DMA_SAFE)
kfree(msg[1].buf);
return 0;
}