diff options
Diffstat (limited to 'drivers/spi/spi-imx.c')
| -rw-r--r-- | drivers/spi/spi-imx.c | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c index 894801ed182b..fe2305e6e38e 100644 --- a/drivers/spi/spi-imx.c +++ b/drivers/spi/spi-imx.c @@ -31,6 +31,12 @@ static bool use_dma = true; module_param(use_dma, bool, 0644); MODULE_PARM_DESC(use_dma, "Enable usage of DMA when available (default)"); +/* define polling limits */ +static unsigned int polling_limit_us = 30; +module_param(polling_limit_us, uint, 0664); +MODULE_PARM_DESC(polling_limit_us, + "time in us to run a transfer in polling mode\n"); + #define MXC_RPM_TIMEOUT 2000 /* 2000ms */ #define MXC_CSPIRXDATA 0x00 @@ -1488,6 +1494,54 @@ static int spi_imx_pio_transfer(struct spi_device *spi, return 0; } +static int spi_imx_poll_transfer(struct spi_device *spi, + struct spi_transfer *transfer) +{ + struct spi_imx_data *spi_imx = spi_controller_get_devdata(spi->controller); + unsigned long timeout; + + spi_imx->tx_buf = transfer->tx_buf; + spi_imx->rx_buf = transfer->rx_buf; + spi_imx->count = transfer->len; + spi_imx->txfifo = 0; + spi_imx->remainder = 0; + + /* fill in the fifo before timeout calculations if we are + * interrupted here, then the data is getting transferred by + * the HW while we are interrupted + */ + spi_imx_push(spi_imx); + + timeout = spi_imx_calculate_timeout(spi_imx, transfer->len) + jiffies; + while (spi_imx->txfifo) { + /* RX */ + while (spi_imx->txfifo && + spi_imx->devtype_data->rx_available(spi_imx)) { + spi_imx->rx(spi_imx); + spi_imx->txfifo--; + } + + /* TX */ + if (spi_imx->count) { + spi_imx_push(spi_imx); + continue; + } + + if (spi_imx->txfifo && + time_after(jiffies, timeout)) { + + dev_err_ratelimited(&spi->dev, + "timeout period reached: jiffies: %lu- falling back to interrupt mode\n", + jiffies - timeout); + + /* fall back to interrupt mode */ + return spi_imx_pio_transfer(spi, transfer); + } + } + + return 0; +} + static int spi_imx_pio_transfer_slave(struct spi_device *spi, struct spi_transfer *transfer) { @@ -1537,6 +1591,7 @@ static int spi_imx_transfer_one(struct spi_controller *controller, struct spi_transfer *transfer) { struct spi_imx_data *spi_imx = spi_controller_get_devdata(spi->controller); + unsigned long hz_per_byte, byte_limit; spi_imx_setupxfer(spi, transfer); transfer->effective_speed_hz = spi_imx->spi_bus_clk; @@ -1548,6 +1603,17 @@ static int spi_imx_transfer_one(struct spi_controller *controller, if (spi_imx->slave_mode) return spi_imx_pio_transfer_slave(spi, transfer); + /* + * Calculate the estimated time in us the transfer runs. Find + * the number of Hz per byte per polling limit. + */ + hz_per_byte = polling_limit_us ? ((8 + 4) * USEC_PER_SEC) / polling_limit_us : 0; + byte_limit = hz_per_byte ? transfer->effective_speed_hz / hz_per_byte : 1; + + /* run in polling mode for short transfers */ + if (transfer->len < byte_limit) + return spi_imx_poll_transfer(spi, transfer); + if (spi_imx->usedma) return spi_imx_dma_transfer(spi_imx, transfer); |