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Commit de6efe0a authored by Feng Tang's avatar Feng Tang Committed by Grant Likely
Browse files

spi/dw_spi: unify the low level read/write routines 



The original version has many duplicated codes for null/u8/u16 case,
so unify them to make it cleaner

Signed-off-by: default avatarFeng Tang <feng.tang@intel.com>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent 0ce790e7

drivers/spi/dw_spi.c

+26 −77
Original line number Diff line number Diff line
@@ -58,8 +58,6 @@ struct chip_data { 
	u8 bits_per_word;

	u16 clk_div;		/* baud rate divider */

	u32 speed_hz;		/* baud rate */

	int (*write)(struct dw_spi *dws);

	int (*read)(struct dw_spi *dws);

	void (*cs_control)(u32 command);

};
@@ -185,80 +183,45 @@ static void flush(struct dw_spi *dws) 
	wait_till_not_busy(dws);

}



static int null_writer(struct dw_spi *dws)

{

	u8 n_bytes = dws->n_bytes;



	if (!(dw_readw(dws, sr) & SR_TF_NOT_FULL)

		|| (dws->tx == dws->tx_end))

		return 0;

	dw_writew(dws, dr, 0);

	dws->tx += n_bytes;



	wait_till_not_busy(dws);

	return 1;

}



static int null_reader(struct dw_spi *dws)

static int dw_writer(struct dw_spi *dws)

{

	u8 n_bytes = dws->n_bytes;

	u16 txw = 0;



	while ((dw_readw(dws, sr) & SR_RF_NOT_EMPT)

		&& (dws->rx < dws->rx_end)) {

		dw_readw(dws, dr);

		dws->rx += n_bytes;

	}

	wait_till_not_busy(dws);

	return dws->rx == dws->rx_end;

}



static int u8_writer(struct dw_spi *dws)

{

	if (!(dw_readw(dws, sr) & SR_TF_NOT_FULL)

		|| (dws->tx == dws->tx_end))

		return 0;



	dw_writew(dws, dr, *(u8 *)(dws->tx));

	++dws->tx;



	wait_till_not_busy(dws);

	return 1;

}



static int u8_reader(struct dw_spi *dws)

{

	while ((dw_readw(dws, sr) & SR_RF_NOT_EMPT)

		&& (dws->rx < dws->rx_end)) {

		*(u8 *)(dws->rx) = dw_readw(dws, dr);

		++dws->rx;

	}



	wait_till_not_busy(dws);

	return dws->rx == dws->rx_end;

	/* Set the tx word if the transfer's original "tx" is not null */

	if (dws->tx_end - dws->len) {

		if (dws->n_bytes == 1)

			txw = *(u8 *)(dws->tx);

		else

			txw = *(u16 *)(dws->tx);

	}



static int u16_writer(struct dw_spi *dws)

{

	if (!(dw_readw(dws, sr) & SR_TF_NOT_FULL)

		|| (dws->tx == dws->tx_end))

		return 0;



	dw_writew(dws, dr, *(u16 *)(dws->tx));

	dws->tx += 2;

	dw_writew(dws, dr, txw);

	dws->tx += dws->n_bytes;



	wait_till_not_busy(dws);

	return 1;

}



static int u16_reader(struct dw_spi *dws)

static int dw_reader(struct dw_spi *dws)

{

	u16 temp;

	u16 rxw;



	while ((dw_readw(dws, sr) & SR_RF_NOT_EMPT)

		&& (dws->rx < dws->rx_end)) {

		temp = dw_readw(dws, dr);

		*(u16 *)(dws->rx) = temp;

		dws->rx += 2;

		rxw = dw_readw(dws, dr);

		/* Care rx only if the transfer's original "rx" is not null */

		if (dws->rx_end - dws->len) {

			if (dws->n_bytes == 1)

				*(u8 *)(dws->rx) = rxw;

			else

				*(u16 *)(dws->rx) = rxw;

		}

		dws->rx += dws->n_bytes;

	}



	wait_till_not_busy(dws);
@@ -383,8 +346,8 @@ static irqreturn_t interrupt_transfer(struct dw_spi *dws) 
		left = (left > int_level) ? int_level : left;



		while (left--)

			dws->write(dws);

		dws->read(dws);

			dw_writer(dws);

		dw_reader(dws);



		/* Re-enable the IRQ if there is still data left to tx */

		if (dws->tx_end > dws->tx)
@@ -417,13 +380,13 @@ static irqreturn_t dw_spi_irq(int irq, void *dev_id) 
/* Must be called inside pump_transfers() */

static void poll_transfer(struct dw_spi *dws)

{

	while (dws->write(dws))

		dws->read(dws);

	while (dw_writer(dws))

		dw_reader(dws);

	/*

	 * There is a possibility that the last word of a transaction

	 * will be lost if data is not ready. Re-read to solve this issue.

	 */

	dws->read(dws);

	dw_reader(dws);



	dw_spi_xfer_done(dws);

}
@@ -483,8 +446,6 @@ static void pump_transfers(unsigned long data) 
	dws->tx_end = dws->tx + transfer->len;

	dws->rx = transfer->rx_buf;

	dws->rx_end = dws->rx + transfer->len;

	dws->write = dws->tx ? chip->write : null_writer;

	dws->read = dws->rx ? chip->read : null_reader;

	dws->cs_change = transfer->cs_change;

	dws->len = dws->cur_transfer->len;

	if (chip != dws->prev_chip)
@@ -520,18 +481,10 @@ static void pump_transfers(unsigned long data) 
		case 8:

			dws->n_bytes = 1;

			dws->dma_width = 1;

			dws->read = (dws->read != null_reader) ?

					u8_reader : null_reader;

			dws->write = (dws->write != null_writer) ?

					u8_writer : null_writer;

			break;

		case 16:

			dws->n_bytes = 2;

			dws->dma_width = 2;

			dws->read = (dws->read != null_reader) ?

					u16_reader : null_reader;

			dws->write = (dws->write != null_writer) ?

					u16_writer : null_writer;

			break;

		default:

			printk(KERN_ERR "MRST SPI0: unsupported bits:"
@@ -733,13 +686,9 @@ static int dw_spi_setup(struct spi_device *spi) 
	if (spi->bits_per_word <= 8) {

		chip->n_bytes = 1;

		chip->dma_width = 1;

		chip->read = u8_reader;

		chip->write = u8_writer;

	} else if (spi->bits_per_word <= 16) {

		chip->n_bytes = 2;

		chip->dma_width = 2;

		chip->read = u16_reader;

		chip->write = u16_writer;

	} else {

		/* Never take >16b case for MRST SPIC */

		dev_err(&spi->dev, "invalid wordsize\n");

drivers/spi/dw_spi.h

+0 −2
Original line number Diff line number Diff line
@@ -137,8 +137,6 @@ struct dw_spi { 
	u8			max_bits_per_word;	/* maxim is 16b */

	u32			dma_width;

	int			cs_change;

	int			(*write)(struct dw_spi *dws);

	int			(*read)(struct dw_spi *dws);

	irqreturn_t		(*transfer_handler)(struct dw_spi *dws);

	void			(*cs_control)(u32 command);