From 75223bbea840e125359fc63942b5f93462b474c6 Mon Sep 17 00:00:00 2001 From: Vaishnav Achath Date: Fri, 13 Oct 2023 14:56:29 +0530 Subject: spi: omap2-mcspi: Add FIFO support without DMA Currently, the built-in 64-byte FIFO on the MCSPI controller is not enabled in PIO mode and is used only when DMA is enabled. Enable the FIFO in PIO mode by default for transactions larger than the FIFO depth and fallback only if FIFO is not available. When DMA is not enabled, it is efficient to enable the RX FIFO almost full and TX FIFO almost empty events after each FIFO fill instead of each word. Update omap2_mcspi_set_fifo() to enable the events accordingly and also rely on OMAP2_MCSPI_CHSTAT_RXS for the last transfer instead of the FIFO events to handle the case when the transfer size is not a multiple of FIFO depth. See J721E Technical Reference Manual (SPRUI1C), section 12.1.5 for further details: http://www.ti.com/lit/pdf/spruil1 Signed-off-by: Vaishnav Achath Link: https://lore.kernel.org/r/20231013092629.19005-1-vaishnav.a@ti.com Signed-off-by: Mark Brown --- drivers/spi/spi-omap2-mcspi.c | 137 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 129 insertions(+), 8 deletions(-) (limited to 'drivers/spi/spi-omap2-mcspi.c') diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c index ddf1c684bcc7..a0c9fea908f5 100644 --- a/drivers/spi/spi-omap2-mcspi.c +++ b/drivers/spi/spi-omap2-mcspi.c @@ -53,6 +53,8 @@ /* per-register bitmasks: */ #define OMAP2_MCSPI_IRQSTATUS_EOW BIT(17) +#define OMAP2_MCSPI_IRQSTATUS_TX0_EMPTY BIT(0) +#define OMAP2_MCSPI_IRQSTATUS_RX0_FULL BIT(2) #define OMAP2_MCSPI_MODULCTRL_SINGLE BIT(0) #define OMAP2_MCSPI_MODULCTRL_MS BIT(2) @@ -291,7 +293,7 @@ static void omap2_mcspi_set_mode(struct spi_controller *ctlr) } static void omap2_mcspi_set_fifo(const struct spi_device *spi, - struct spi_transfer *t, int enable) + struct spi_transfer *t, int enable, int dma_enabled) { struct spi_controller *ctlr = spi->controller; struct omap2_mcspi_cs *cs = spi->controller_state; @@ -312,20 +314,28 @@ static void omap2_mcspi_set_fifo(const struct spi_device *spi, max_fifo_depth = OMAP2_MCSPI_MAX_FIFODEPTH / 2; else max_fifo_depth = OMAP2_MCSPI_MAX_FIFODEPTH; - - wcnt = t->len / bytes_per_word; + if (dma_enabled) + wcnt = t->len / bytes_per_word; + else + wcnt = 0; if (wcnt > OMAP2_MCSPI_MAX_FIFOWCNT) goto disable_fifo; xferlevel = wcnt << 16; if (t->rx_buf != NULL) { chconf |= OMAP2_MCSPI_CHCONF_FFER; - xferlevel |= (bytes_per_word - 1) << 8; + if (dma_enabled) + xferlevel |= (bytes_per_word - 1) << 8; + else + xferlevel |= (max_fifo_depth - 1) << 8; } if (t->tx_buf != NULL) { chconf |= OMAP2_MCSPI_CHCONF_FFET; - xferlevel |= bytes_per_word - 1; + if (dma_enabled) + xferlevel |= bytes_per_word - 1; + else + xferlevel |= (max_fifo_depth - 1); } mcspi_write_reg(ctlr, OMAP2_MCSPI_XFERLEVEL, xferlevel); @@ -882,6 +892,113 @@ out: return count - c; } +static unsigned +omap2_mcspi_txrx_piofifo(struct spi_device *spi, struct spi_transfer *xfer) +{ + struct omap2_mcspi_cs *cs = spi->controller_state; + struct omap2_mcspi *mcspi; + unsigned int count, c; + unsigned int iter, cwc; + int last_request; + void __iomem *base = cs->base; + void __iomem *tx_reg; + void __iomem *rx_reg; + void __iomem *chstat_reg; + void __iomem *irqstat_reg; + int word_len, bytes_per_word; + u8 *rx; + const u8 *tx; + + mcspi = spi_controller_get_devdata(spi->controller); + count = xfer->len; + c = count; + word_len = cs->word_len; + bytes_per_word = mcspi_bytes_per_word(word_len); + + /* + * We store the pre-calculated register addresses on stack to speed + * up the transfer loop. + */ + tx_reg = base + OMAP2_MCSPI_TX0; + rx_reg = base + OMAP2_MCSPI_RX0; + chstat_reg = base + OMAP2_MCSPI_CHSTAT0; + irqstat_reg = base + OMAP2_MCSPI_IRQSTATUS; + + if (c < (word_len >> 3)) + return 0; + + rx = xfer->rx_buf; + tx = xfer->tx_buf; + + do { + /* calculate number of words in current iteration */ + cwc = min((unsigned int)mcspi->fifo_depth / bytes_per_word, + c / bytes_per_word); + last_request = cwc != (mcspi->fifo_depth / bytes_per_word); + if (tx) { + if (mcspi_wait_for_reg_bit(irqstat_reg, + OMAP2_MCSPI_IRQSTATUS_TX0_EMPTY) < 0) { + dev_err(&spi->dev, "TX Empty timed out\n"); + goto out; + } + writel_relaxed(OMAP2_MCSPI_IRQSTATUS_TX0_EMPTY, irqstat_reg); + + for (iter = 0; iter < cwc; iter++, tx += bytes_per_word) { + if (bytes_per_word == 1) + writel_relaxed(*tx, tx_reg); + else if (bytes_per_word == 2) + writel_relaxed(*((u16 *)tx), tx_reg); + else if (bytes_per_word == 4) + writel_relaxed(*((u32 *)tx), tx_reg); + } + } + + if (rx) { + if (!last_request && + mcspi_wait_for_reg_bit(irqstat_reg, + OMAP2_MCSPI_IRQSTATUS_RX0_FULL) < 0) { + dev_err(&spi->dev, "RX_FULL timed out\n"); + goto out; + } + writel_relaxed(OMAP2_MCSPI_IRQSTATUS_RX0_FULL, irqstat_reg); + + for (iter = 0; iter < cwc; iter++, rx += bytes_per_word) { + if (last_request && + mcspi_wait_for_reg_bit(chstat_reg, + OMAP2_MCSPI_CHSTAT_RXS) < 0) { + dev_err(&spi->dev, "RXS timed out\n"); + goto out; + } + if (bytes_per_word == 1) + *rx = readl_relaxed(rx_reg); + else if (bytes_per_word == 2) + *((u16 *)rx) = readl_relaxed(rx_reg); + else if (bytes_per_word == 4) + *((u32 *)rx) = readl_relaxed(rx_reg); + } + } + + if (last_request) { + if (mcspi_wait_for_reg_bit(chstat_reg, + OMAP2_MCSPI_CHSTAT_EOT) < 0) { + dev_err(&spi->dev, "EOT timed out\n"); + goto out; + } + if (mcspi_wait_for_reg_bit(chstat_reg, + OMAP2_MCSPI_CHSTAT_TXFFE) < 0) { + dev_err(&spi->dev, "TXFFE timed out\n"); + goto out; + } + omap2_mcspi_set_enable(spi, 0); + } + c -= cwc * bytes_per_word; + } while (c >= bytes_per_word); + +out: + omap2_mcspi_set_enable(spi, 1); + return count - c; +} + static u32 omap2_mcspi_calc_divisor(u32 speed_hz, u32 ref_clk_hz) { u32 div; @@ -1206,7 +1323,9 @@ static int omap2_mcspi_transfer_one(struct spi_controller *ctlr, if ((mcspi_dma->dma_rx && mcspi_dma->dma_tx) && ctlr->cur_msg_mapped && ctlr->can_dma(ctlr, spi, t)) - omap2_mcspi_set_fifo(spi, t, 1); + omap2_mcspi_set_fifo(spi, t, 1, 1); + else if (t->len > OMAP2_MCSPI_MAX_FIFODEPTH) + omap2_mcspi_set_fifo(spi, t, 1, 0); omap2_mcspi_set_enable(spi, 1); @@ -1219,6 +1338,8 @@ static int omap2_mcspi_transfer_one(struct spi_controller *ctlr, ctlr->cur_msg_mapped && ctlr->can_dma(ctlr, spi, t)) count = omap2_mcspi_txrx_dma(spi, t); + else if (mcspi->fifo_depth > 0) + count = omap2_mcspi_txrx_piofifo(spi, t); else count = omap2_mcspi_txrx_pio(spi, t); @@ -1231,7 +1352,7 @@ static int omap2_mcspi_transfer_one(struct spi_controller *ctlr, omap2_mcspi_set_enable(spi, 0); if (mcspi->fifo_depth > 0) - omap2_mcspi_set_fifo(spi, t, 0); + omap2_mcspi_set_fifo(spi, t, 0, 0); out: /* Restore defaults if they were overriden */ @@ -1254,7 +1375,7 @@ out: omap2_mcspi_set_cs(spi, !(spi->mode & SPI_CS_HIGH)); if (mcspi->fifo_depth > 0 && t) - omap2_mcspi_set_fifo(spi, t, 0); + omap2_mcspi_set_fifo(spi, t, 0, 0); return status; } -- cgit v1.2.3