i2c: at91: fix support of the "alternative command" feature

[cascardo/linux.git] / drivers / i2c / busses / i2c-at91.c

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index f233726..1bb97f6 100644 (file)
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -38,6 +38,7 @@
 #define AT91_I2C_TIMEOUT       msecs_to_jiffies(100)   /* transfer timeout */
 #define AT91_I2C_DMA_THRESHOLD 8                       /* enable DMA if transfer size is bigger than this threshold */
 #define AUTOSUSPEND_TIMEOUT            2000
+#define AT91_I2C_MAX_ALT_CMD_DATA_SIZE 256
 
 /* AT91 TWI register definitions */
 #define        AT91_TWI_CR             0x0000  /* Control Register */
@@ -141,6 +142,7 @@ struct at91_twi_dev {
        unsigned twi_cwgr_reg;
        struct at91_twi_pdata *pdata;
        bool use_dma;
+       bool use_alt_cmd;
        bool recv_len_abort;
        u32 fifo_size;
        struct at91_twi_dma dma;
@@ -269,7 +271,7 @@ static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
 
        /* send stop when last byte has been written */
        if (--dev->buf_len == 0)
-               if (!dev->pdata->has_alt_cmd)
+               if (!dev->use_alt_cmd)
                        at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
 
        dev_dbg(dev->dev, "wrote 0x%x, to go %d\n", *dev->buf, dev->buf_len);
@@ -292,7 +294,7 @@ static void at91_twi_write_data_dma_callback(void *data)
         * we just have to enable TXCOMP one.
         */
        at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP);
-       if (!dev->pdata->has_alt_cmd)
+       if (!dev->use_alt_cmd)
                at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
 }
 
@@ -410,7 +412,7 @@ static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
        }
 
        /* send stop if second but last byte has been read */
-       if (!dev->pdata->has_alt_cmd && dev->buf_len == 1)
+       if (!dev->use_alt_cmd && dev->buf_len == 1)
                at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
 
        dev_dbg(dev->dev, "read 0x%x, to go %d\n", *dev->buf, dev->buf_len);
@@ -426,7 +428,7 @@ static void at91_twi_read_data_dma_callback(void *data)
        dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg[0]),
                         dev->buf_len, DMA_FROM_DEVICE);
 
-       if (!dev->pdata->has_alt_cmd) {
+       if (!dev->use_alt_cmd) {
                /* The last two bytes have to be read without using dma */
                dev->buf += dev->buf_len - 2;
                dev->buf_len = 2;
@@ -443,7 +445,7 @@ static void at91_twi_read_data_dma(struct at91_twi_dev *dev)
        struct dma_chan *chan_rx = dma->chan_rx;
        size_t buf_len;
 
-       buf_len = (dev->pdata->has_alt_cmd) ? dev->buf_len : dev->buf_len - 2;
+       buf_len = (dev->use_alt_cmd) ? dev->buf_len : dev->buf_len - 2;
        dma->direction = DMA_FROM_DEVICE;
 
        /* Keep in mind that we won't use dma to read the last two bytes */
@@ -651,7 +653,7 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
                unsigned start_flags = AT91_TWI_START;
 
                /* if only one byte is to be read, immediately stop transfer */
-               if (!has_alt_cmd && dev->buf_len <= 1 &&
+               if (!dev->use_alt_cmd && dev->buf_len <= 1 &&
                    !(dev->msg->flags & I2C_M_RECV_LEN))
                        start_flags |= AT91_TWI_STOP;
                at91_twi_write(dev, AT91_TWI_CR, start_flags);
@@ -745,7 +747,7 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
        int ret;
        unsigned int_addr_flag = 0;
        struct i2c_msg *m_start = msg;
-       bool is_read, use_alt_cmd = false;
+       bool is_read;
 
        dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
 
@@ -768,14 +770,16 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
                at91_twi_write(dev, AT91_TWI_IADR, internal_address);
        }
 
+       dev->use_alt_cmd = false;
        is_read = (m_start->flags & I2C_M_RD);
        if (dev->pdata->has_alt_cmd) {
-               if (m_start->len > 0) {
+               if (m_start->len > 0 &&
+                   m_start->len < AT91_I2C_MAX_ALT_CMD_DATA_SIZE) {
                        at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_ACMEN);
                        at91_twi_write(dev, AT91_TWI_ACR,
                                       AT91_TWI_ACR_DATAL(m_start->len) |
                                       ((is_read) ? AT91_TWI_ACR_DIR : 0));
-                       use_alt_cmd = true;
+                       dev->use_alt_cmd = true;
                } else {
                        at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_ACMDIS);
                }
@@ -784,7 +788,7 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
        at91_twi_write(dev, AT91_TWI_MMR,
                       (m_start->addr << 16) |
                       int_addr_flag |
-                      ((!use_alt_cmd && is_read) ? AT91_TWI_MREAD : 0));
+                      ((!dev->use_alt_cmd && is_read) ? AT91_TWI_MREAD : 0));
 
        dev->buf_len = m_start->len;
        dev->buf = m_start->buf;