diff options
Diffstat (limited to 'drivers/spi/spi-imx.c')
| -rw-r--r-- | drivers/spi/spi-imx.c | 66 |
1 files changed, 61 insertions, 5 deletions
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c index 15323d8bd9c..47f15d97e7f 100644 --- a/drivers/spi/spi-imx.c +++ b/drivers/spi/spi-imx.c @@ -206,7 +206,8 @@ static unsigned int spi_imx_clkdiv_2(unsigned int fin, #define MX51_ECSPI_STAT_RR (1 << 3) /* MX51 eCSPI */ -static unsigned int mx51_ecspi_clkdiv(unsigned int fin, unsigned int fspi) +static unsigned int mx51_ecspi_clkdiv(unsigned int fin, unsigned int fspi, + unsigned int *fres) { /* * there are two 4-bit dividers, the pre-divider divides by @@ -234,6 +235,10 @@ static unsigned int mx51_ecspi_clkdiv(unsigned int fin, unsigned int fspi) pr_debug("%s: fin: %u, fspi: %u, post: %u, pre: %u\n", __func__, fin, fspi, post, pre); + + /* Resulting frequency for the SCLK line. */ + *fres = (fin / (pre + 1)) >> post; + return (pre << MX51_ECSPI_CTRL_PREDIV_OFFSET) | (post << MX51_ECSPI_CTRL_POSTDIV_OFFSET); } @@ -264,6 +269,7 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx, struct spi_imx_config *config) { u32 ctrl = MX51_ECSPI_CTRL_ENABLE, cfg = 0; + u32 clk = config->speed_hz, delay; /* * The hardware seems to have a race condition when changing modes. The @@ -275,7 +281,7 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx, ctrl |= MX51_ECSPI_CTRL_MODE_MASK; /* set clock speed */ - ctrl |= mx51_ecspi_clkdiv(spi_imx->spi_clk, config->speed_hz); + ctrl |= mx51_ecspi_clkdiv(spi_imx->spi_clk, config->speed_hz, &clk); /* set chip select to use */ ctrl |= MX51_ECSPI_CTRL_CS(config->cs); @@ -297,6 +303,23 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx, writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL); writel(cfg, spi_imx->base + MX51_ECSPI_CONFIG); + /* + * Wait until the changes in the configuration register CONFIGREG + * propagate into the hardware. It takes exactly one tick of the + * SCLK clock, but we will wait two SCLK clock just to be sure. The + * effect of the delay it takes for the hardware to apply changes + * is noticable if the SCLK clock run very slow. In such a case, if + * the polarity of SCLK should be inverted, the GPIO ChipSelect might + * be asserted before the SCLK polarity changes, which would disrupt + * the SPI communication as the device on the other end would consider + * the change of SCLK polarity as a clock tick already. + */ + delay = (2 * 1000000) / clk; + if (likely(delay < 10)) /* SCLK is faster than 100 kHz */ + udelay(delay); + else /* SCLK is _very_ slow */ + usleep_range(delay, delay + 10); + return 0; } @@ -749,6 +772,35 @@ static void spi_imx_cleanup(struct spi_device *spi) { } +static int +spi_imx_prepare_message(struct spi_master *master, struct spi_message *msg) +{ + struct spi_imx_data *spi_imx = spi_master_get_devdata(master); + int ret; + + ret = clk_enable(spi_imx->clk_per); + if (ret) + return ret; + + ret = clk_enable(spi_imx->clk_ipg); + if (ret) { + clk_disable(spi_imx->clk_per); + return ret; + } + + return 0; +} + +static int +spi_imx_unprepare_message(struct spi_master *master, struct spi_message *msg) +{ + struct spi_imx_data *spi_imx = spi_master_get_devdata(master); + + clk_disable(spi_imx->clk_ipg); + clk_disable(spi_imx->clk_per); + return 0; +} + static int spi_imx_probe(struct platform_device *pdev) { struct device_node *np = pdev->dev.of_node; @@ -786,7 +838,7 @@ static int spi_imx_probe(struct platform_device *pdev) master->num_chipselect = num_cs; spi_imx = spi_master_get_devdata(master); - spi_imx->bitbang.master = spi_master_get(master); + spi_imx->bitbang.master = master; for (i = 0; i < master->num_chipselect; i++) { int cs_gpio = of_get_named_gpio(np, "cs-gpios", i); @@ -810,6 +862,8 @@ static int spi_imx_probe(struct platform_device *pdev) spi_imx->bitbang.txrx_bufs = spi_imx_transfer; spi_imx->bitbang.master->setup = spi_imx_setup; spi_imx->bitbang.master->cleanup = spi_imx_cleanup; + spi_imx->bitbang.master->prepare_message = spi_imx_prepare_message; + spi_imx->bitbang.master->unprepare_message = spi_imx_unprepare_message; spi_imx->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH; init_completion(&spi_imx->xfer_done); @@ -872,6 +926,8 @@ static int spi_imx_probe(struct platform_device *pdev) dev_info(&pdev->dev, "probed\n"); + clk_disable(spi_imx->clk_ipg); + clk_disable(spi_imx->clk_per); return ret; out_clk_put: @@ -892,8 +948,8 @@ static int spi_imx_remove(struct platform_device *pdev) spi_bitbang_stop(&spi_imx->bitbang); writel(0, spi_imx->base + MXC_CSPICTRL); - clk_disable_unprepare(spi_imx->clk_ipg); - clk_disable_unprepare(spi_imx->clk_per); + clk_unprepare(spi_imx->clk_ipg); + clk_unprepare(spi_imx->clk_per); spi_master_put(master); return 0; |