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 <Sergey.Semin@baikalelectronics.ru> Link: https://lore.kernel.org/r/20201007235511.4935-9-Sergey.Semin@baikalelectronics.ru Signed-off-by: Mark Brown <broonie@kernel.org>
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@ -108,9 +108,8 @@ EXPORT_SYMBOL_GPL(dw_spi_set_cs);
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/* Return the max entries we can fill into tx fifo */
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/* Return the max entries we can fill into tx fifo */
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static inline u32 tx_max(struct dw_spi *dws)
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static inline u32 tx_max(struct dw_spi *dws)
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{
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{
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u32 tx_left, tx_room, rxtx_gap;
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u32 tx_room, rxtx_gap;
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tx_left = (dws->tx_end - dws->tx) / dws->n_bytes;
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tx_room = dws->fifo_len - dw_readl(dws, DW_SPI_TXFLR);
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tx_room = dws->fifo_len - dw_readl(dws, DW_SPI_TXFLR);
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/*
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/*
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@ -121,18 +120,15 @@ static inline u32 tx_max(struct dw_spi *dws)
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* shift registers. So a control from sw point of
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* shift registers. So a control from sw point of
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* view is taken.
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* view is taken.
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*/
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*/
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rxtx_gap = ((dws->rx_end - dws->rx) - (dws->tx_end - dws->tx))
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rxtx_gap = dws->fifo_len - (dws->rx_len - dws->tx_len);
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/ dws->n_bytes;
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return min3(tx_left, tx_room, (u32) (dws->fifo_len - rxtx_gap));
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return min3((u32)dws->tx_len, tx_room, rxtx_gap);
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}
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}
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/* Return the max entries we should read out of rx fifo */
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/* Return the max entries we should read out of rx fifo */
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static inline u32 rx_max(struct dw_spi *dws)
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static inline u32 rx_max(struct dw_spi *dws)
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{
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{
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u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes;
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return min_t(u32, dws->rx_len, dw_readl(dws, DW_SPI_RXFLR));
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return min_t(u32, rx_left, dw_readl(dws, DW_SPI_RXFLR));
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}
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}
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static void dw_writer(struct dw_spi *dws)
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static void dw_writer(struct dw_spi *dws)
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@ -141,15 +137,16 @@ static void dw_writer(struct dw_spi *dws)
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u16 txw = 0;
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u16 txw = 0;
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while (max--) {
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while (max--) {
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/* Set the tx word if the transfer's original "tx" is not null */
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if (dws->tx) {
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if (dws->tx_end - dws->len) {
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if (dws->n_bytes == 1)
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if (dws->n_bytes == 1)
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txw = *(u8 *)(dws->tx);
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txw = *(u8 *)(dws->tx);
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else
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else
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txw = *(u16 *)(dws->tx);
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txw = *(u16 *)(dws->tx);
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dws->tx += dws->n_bytes;
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}
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}
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dw_write_io_reg(dws, DW_SPI_DR, txw);
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dw_write_io_reg(dws, DW_SPI_DR, txw);
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dws->tx += dws->n_bytes;
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--dws->tx_len;
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}
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}
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}
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}
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@ -160,14 +157,15 @@ static void dw_reader(struct dw_spi *dws)
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while (max--) {
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while (max--) {
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rxw = dw_read_io_reg(dws, DW_SPI_DR);
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rxw = dw_read_io_reg(dws, DW_SPI_DR);
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/* Care rx only if the transfer's original "rx" is not null */
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if (dws->rx) {
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if (dws->rx_end - dws->len) {
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if (dws->n_bytes == 1)
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if (dws->n_bytes == 1)
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*(u8 *)(dws->rx) = rxw;
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*(u8 *)(dws->rx) = rxw;
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else
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else
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*(u16 *)(dws->rx) = rxw;
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*(u16 *)(dws->rx) = rxw;
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dws->rx += dws->n_bytes;
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}
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}
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dws->rx += dws->n_bytes;
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--dws->rx_len;
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}
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}
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}
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}
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@ -192,7 +190,7 @@ static irqreturn_t interrupt_transfer(struct dw_spi *dws)
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}
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}
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dw_reader(dws);
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dw_reader(dws);
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if (dws->rx_end == dws->rx) {
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if (!dws->rx_len) {
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spi_mask_intr(dws, 0xff);
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spi_mask_intr(dws, 0xff);
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spi_finalize_current_transfer(dws->master);
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spi_finalize_current_transfer(dws->master);
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return IRQ_HANDLED;
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return IRQ_HANDLED;
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@ -320,12 +318,11 @@ static int dw_spi_transfer_one(struct spi_controller *master,
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dws->dma_mapped = 0;
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dws->dma_mapped = 0;
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dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
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dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
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dws->tx = (void *)transfer->tx_buf;
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dws->tx = (void *)transfer->tx_buf;
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dws->tx_end = dws->tx + transfer->len;
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dws->tx_len = transfer->len / dws->n_bytes;
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dws->rx = transfer->rx_buf;
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dws->rx = transfer->rx_buf;
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dws->rx_end = dws->rx + transfer->len;
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dws->rx_len = dws->tx_len;
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dws->len = transfer->len;
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/* Ensure dw->rx and dw->rx_end are visible */
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/* Ensure the data above is visible for all CPUs */
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smp_mb();
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smp_mb();
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spi_enable_chip(dws, 0);
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spi_enable_chip(dws, 0);
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@ -352,7 +349,7 @@ static int dw_spi_transfer_one(struct spi_controller *master,
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return ret;
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return ret;
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}
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}
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} else {
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} else {
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txlevel = min_t(u16, dws->fifo_len / 2, dws->len / dws->n_bytes);
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txlevel = min_t(u16, dws->fifo_len / 2, dws->tx_len);
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dw_writel(dws, DW_SPI_TXFTLR, txlevel);
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dw_writel(dws, DW_SPI_TXFTLR, txlevel);
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/* Set the interrupt mask */
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/* Set the interrupt mask */
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@ -147,11 +147,10 @@ struct dw_spi {
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void (*set_cs)(struct spi_device *spi, bool enable);
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void (*set_cs)(struct spi_device *spi, bool enable);
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/* Current message transfer state info */
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/* Current message transfer state info */
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size_t len;
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void *tx;
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void *tx;
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void *tx_end;
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unsigned int tx_len;
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void *rx;
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void *rx;
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void *rx_end;
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unsigned int rx_len;
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int dma_mapped;
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int dma_mapped;
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u8 n_bytes; /* current is a 1/2 bytes op */
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u8 n_bytes; /* current is a 1/2 bytes op */
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irqreturn_t (*transfer_handler)(struct dw_spi *dws);
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irqreturn_t (*transfer_handler)(struct dw_spi *dws);
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