From 8a77821e74d6d5ba2eacd4b450684ae6cbe012a0 Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Sat, 4 Nov 2017 21:20:06 +0100 Subject: i2c: smbus: use DMA safe buffers for emulated SMBus transactions 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 Reviewed-by: Jonathan Cameron Signed-off-by: Wolfram Sang --- drivers/i2c/i2c-core-smbus.c | 45 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 39 insertions(+), 6 deletions(-) (limited to 'drivers/i2c/i2c-core-smbus.c') diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c index 4bb9927afd01..1238c94fe5a1 100644 --- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -18,6 +18,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -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; } -- cgit