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