From 8dedbeac8ab24d2da9271df2c8291971169846f2 Mon Sep 17 00:00:00 2001 From: Serge Semin Date: Thu, 8 Oct 2020 02:54:57 +0300 Subject: [PATCH] spi: dw: Refactor data IO procedure The Tx and Rx data write/read procedure can be significantly simplified by using Tx/Rx transfer lengths instead of the end pointers. By having the Tx/Rx data leftover lengths (in the number of transfer words) we can get rid of all subtraction and division operations utilized here and there in the tx_max(), rx_max(), dw_writer() and dw_reader() methods. Such modification will not only give us the more optimized IO procedures, but will make the data IO methods much more readable than before. Signed-off-by: Serge Semin Link: https://lore.kernel.org/r/20201007235511.4935-9-Sergey.Semin@baikalelectronics.ru Signed-off-by: Mark Brown --- drivers/spi/spi-dw-core.c | 37 +++++++++++++++++-------------------- drivers/spi/spi-dw.h | 5 ++--- 2 files changed, 19 insertions(+), 23 deletions(-) diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c index 01ab743..3bb8aa3 100644 --- a/drivers/spi/spi-dw-core.c +++ b/drivers/spi/spi-dw-core.c @@ -108,9 +108,8 @@ EXPORT_SYMBOL_GPL(dw_spi_set_cs); /* Return the max entries we can fill into tx fifo */ static inline u32 tx_max(struct dw_spi *dws) { - u32 tx_left, tx_room, rxtx_gap; + u32 tx_room, rxtx_gap; - tx_left = (dws->tx_end - dws->tx) / dws->n_bytes; tx_room = dws->fifo_len - dw_readl(dws, DW_SPI_TXFLR); /* @@ -121,18 +120,15 @@ static inline u32 tx_max(struct dw_spi *dws) * shift registers. So a control from sw point of * view is taken. */ - rxtx_gap = ((dws->rx_end - dws->rx) - (dws->tx_end - dws->tx)) - / dws->n_bytes; + rxtx_gap = dws->fifo_len - (dws->rx_len - dws->tx_len); - return min3(tx_left, tx_room, (u32) (dws->fifo_len - rxtx_gap)); + return min3((u32)dws->tx_len, tx_room, rxtx_gap); } /* Return the max entries we should read out of rx fifo */ static inline u32 rx_max(struct dw_spi *dws) { - u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes; - - return min_t(u32, rx_left, dw_readl(dws, DW_SPI_RXFLR)); + return min_t(u32, dws->rx_len, dw_readl(dws, DW_SPI_RXFLR)); } static void dw_writer(struct dw_spi *dws) @@ -141,15 +137,16 @@ static void dw_writer(struct dw_spi *dws) u16 txw = 0; while (max--) { - /* Set the tx word if the transfer's original "tx" is not null */ - if (dws->tx_end - dws->len) { + if (dws->tx) { if (dws->n_bytes == 1) txw = *(u8 *)(dws->tx); else txw = *(u16 *)(dws->tx); + + dws->tx += dws->n_bytes; } dw_write_io_reg(dws, DW_SPI_DR, txw); - dws->tx += dws->n_bytes; + --dws->tx_len; } } @@ -160,14 +157,15 @@ static void dw_reader(struct dw_spi *dws) while (max--) { rxw = dw_read_io_reg(dws, DW_SPI_DR); - /* Care rx only if the transfer's original "rx" is not null */ - if (dws->rx_end - dws->len) { + if (dws->rx) { if (dws->n_bytes == 1) *(u8 *)(dws->rx) = rxw; else *(u16 *)(dws->rx) = rxw; + + dws->rx += dws->n_bytes; } - dws->rx += dws->n_bytes; + --dws->rx_len; } } @@ -192,7 +190,7 @@ static irqreturn_t interrupt_transfer(struct dw_spi *dws) } dw_reader(dws); - if (dws->rx_end == dws->rx) { + if (!dws->rx_len) { spi_mask_intr(dws, 0xff); spi_finalize_current_transfer(dws->master); return IRQ_HANDLED; @@ -320,12 +318,11 @@ static int dw_spi_transfer_one(struct spi_controller *master, dws->dma_mapped = 0; dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE); dws->tx = (void *)transfer->tx_buf; - dws->tx_end = dws->tx + transfer->len; + dws->tx_len = transfer->len / dws->n_bytes; dws->rx = transfer->rx_buf; - dws->rx_end = dws->rx + transfer->len; - dws->len = transfer->len; + dws->rx_len = dws->tx_len; - /* Ensure dw->rx and dw->rx_end are visible */ + /* Ensure the data above is visible for all CPUs */ smp_mb(); spi_enable_chip(dws, 0); @@ -352,7 +349,7 @@ static int dw_spi_transfer_one(struct spi_controller *master, return ret; } } else { - txlevel = min_t(u16, dws->fifo_len / 2, dws->len / dws->n_bytes); + txlevel = min_t(u16, dws->fifo_len / 2, dws->tx_len); dw_writel(dws, DW_SPI_TXFTLR, txlevel); /* Set the interrupt mask */ diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h index 14f9b64..70fc9db 100644 --- a/drivers/spi/spi-dw.h +++ b/drivers/spi/spi-dw.h @@ -147,11 +147,10 @@ struct dw_spi { void (*set_cs)(struct spi_device *spi, bool enable); /* Current message transfer state info */ - size_t len; void *tx; - void *tx_end; + unsigned int tx_len; void *rx; - void *rx_end; + unsigned int rx_len; int dma_mapped; u8 n_bytes; /* current is a 1/2 bytes op */ irqreturn_t (*transfer_handler)(struct dw_spi *dws); -- 2.7.4