Messages in this thread Patch in this message |  | | From | Lee Jones <> | Subject | [PATCH 03/10] mtd: st_spi_fsm: Initialise and configure the FSM for normal working conditions | Date | Thu, 14 Nov 2013 14:22:29 +0000 |
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This patch uses default values to initialise a connected flash chip. This includes; a device soft reset, setting of a safe working frequency, a switch into Fast Sequencing Mode, configuring of timing data and a purge of the FIFO.
Signed-off-by: Lee Jones <lee.jones@linaro.org> --- drivers/mtd/devices/st_spi_fsm.c | 123 +++++++++++++++++++++++++++++++++++++++ drivers/mtd/devices/st_spi_fsm.h | 4 ++ 2 files changed, 127 insertions(+)
diff --git a/drivers/mtd/devices/st_spi_fsm.c b/drivers/mtd/devices/st_spi_fsm.c index 689f059..f560343 100644 --- a/drivers/mtd/devices/st_spi_fsm.c +++ b/drivers/mtd/devices/st_spi_fsm.c @@ -25,19 +25,136 @@ #include "st_spi_fsm.h" +#define STFSM_DEFAULT_EMI_FREQ 100000000UL /* 100 MHz */ +#define STFSM_DEFAULT_WR_TIME STFSM_DEFAULT_EMI_FREQ * (15/1000) /* 15ms */ + +#define FLASH_SAFE_FREQ 10000000UL /* 10 MHz */ + struct stfsm { struct device *dev; void __iomem *base; struct resource *region; struct mtd_info mtd; struct mutex lock; + + uint32_t fifo_dir_delay; }; +static inline uint32_t stfsm_fifo_available(struct stfsm *fsm) +{ + return (readl(fsm->base + SPI_FAST_SEQ_STA) >> 5) & 0x7f; +} + +static void stfsm_clear_fifo(struct stfsm *fsm) +{ + uint32_t avail; + + for (;;) { + avail = stfsm_fifo_available(fsm); + if (!avail) + break; + + while (avail) { + readl(fsm->base + SPI_FAST_SEQ_DATA_REG); + avail--; + } + } +} + +static int stfsm_set_mode(struct stfsm *fsm, uint32_t mode) +{ + int ret, timeout = 10; + + /* Wait for controller to accept mode change */ + while(--timeout) { + ret = readl(fsm->base + SPI_STA_MODE_CHANGE); + if (ret & 0x1) + break; + udelay(1); + } + + if (!timeout) + return -EBUSY; + + writel(mode, fsm->base + SPI_MODESELECT); + + return 0; +} + +static void stfsm_set_freq(struct stfsm *fsm, uint32_t spi_freq) +{ + uint32_t emi_freq; + uint32_t clk_div; + + /* TODO: Make this dynamic */ + emi_freq = STFSM_DEFAULT_EMI_FREQ; + + /* + * Calculate clk_div - values between 2 and 128 + * Multiple of 2, rounded up + */ + clk_div = 2*((emi_freq + (2*spi_freq - 1))/(2*spi_freq)); + if (clk_div < 2) + clk_div = 2; + else if (clk_div > 128) + clk_div = 128; + + /* + * Determine a suitable delay for the IP to complete a change of + * direction of the FIFO. The required delay is related to the clock + * divider used. The following heuristics are based on empirical tests, + * using a 100MHz EMI clock. + */ + if (clk_div <= 4) + fsm->fifo_dir_delay = 0; + else if (clk_div <= 10) + fsm->fifo_dir_delay = 1; + else + fsm->fifo_dir_delay = (clk_div + 9) / 10; + + dev_dbg(fsm->dev, "emi_clk = %uHZ, spi_freq = %uHZ, clk_div = %u\n", + emi_freq, spi_freq, clk_div); + + writel(clk_div, fsm->base + SPI_CLOCKDIV); +} + +static int stfsm_init(struct stfsm *fsm) +{ + int ret; + + /* Perform a soft reset of the FSM controller */ + writel(SEQ_CFG_SWRESET, fsm->base + SPI_FAST_SEQ_CFG); + udelay(1); + writel(0, fsm->base + SPI_FAST_SEQ_CFG); + + /* Set clock to 'safe' frequency initially */ + stfsm_set_freq(fsm, FLASH_SAFE_FREQ); + + /* Switch to FSM */ + ret = stfsm_set_mode(fsm, SPI_MODESELECT_FSM); + if (ret) + return ret; + + /* Set timing parameters */ + writel(SPI_CFG_DEVICE_ST | + SPI_CFG_DEFAULT_MIN_CS_HIGH | + SPI_CFG_DEFAULT_CS_SETUPHOLD | + SPI_CFG_DEFAULT_DATA_HOLD, + fsm->base + SPI_CONFIGDATA); + writel(STFSM_DEFAULT_WR_TIME, fsm->base + SPI_STATUS_WR_TIME_REG); + + /* Clear FIFO, just in case */ + stfsm_clear_fifo(fsm); + + return 0; +} + static int stfsm_probe(struct platform_device *pdev) { struct device_node *np = pdev->dev.of_node; struct resource *res; struct stfsm *fsm; + int ret; if (!np) { dev_err(&pdev->dev, "No DT found\n"); @@ -74,6 +191,12 @@ static int stfsm_probe(struct platform_device *pdev) mutex_init(&fsm->lock); + ret = stfsm_init(fsm); + if (ret) { + dev_err(&pdev->dev, "Failed to initialise FSM Controller\n"); + return ret; + } + platform_set_drvdata(pdev, fsm); fsm->mtd.dev.parent = &pdev->dev; diff --git a/drivers/mtd/devices/st_spi_fsm.h b/drivers/mtd/devices/st_spi_fsm.h index 11ca33a..7a8f1eb 100644 --- a/drivers/mtd/devices/st_spi_fsm.h +++ b/drivers/mtd/devices/st_spi_fsm.h @@ -69,6 +69,10 @@ #define SPI_CFG_CS_SETUPHOLD(x) (((x) & 0xff) << 16) #define SPI_CFG_DATA_HOLD(x) (((x) & 0xff) << 24) +#define SPI_CFG_DEFAULT_MIN_CS_HIGH SPI_CFG_MIN_CS_HIGH(0x0AA) +#define SPI_CFG_DEFAULT_CS_SETUPHOLD SPI_CFG_CS_SETUPHOLD(0xA0) +#define SPI_CFG_DEFAULT_DATA_HOLD SPI_CFG_DATA_HOLD(0x00) + /* * Register: SPI_FAST_SEQ_TRANSFER_SIZE */ -- 1.8.1.2
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