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spi/dw_spi: refine the IRQ mode working flow 

Now dw_spi core fully supports 3 transfer modes: pure polling,
DMA and IRQ mode. IRQ mode will use the FIFO half empty as
the IRQ trigger, so each interface driver need set the fifo_len,
so that core driver can handle it properly

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Feng Tang 2010-01-20 13:49:45 -07:00 committed by Grant Likely
parent 51f921c1eb
commit 552e450929
3 changed files with 44 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

70
drivers/spi/dw_spi.c
View File

@ -358,6 +358,8 @@ static void transfer_complete(struct dw_spi *dws)
static irqreturn_t interrupt_transfer(struct dw_spi *dws)
{
u16 irq_status, irq_mask = 0x3f;
u32 int_level = dws->fifo_len / 2;
u32 left;
irq_status = dw_readw(dws, isr) & irq_mask;
/* Error handling */
@ -369,22 +371,23 @@ static irqreturn_t interrupt_transfer(struct dw_spi *dws)
return IRQ_HANDLED;
}
/* INT comes from tx */
if (dws->tx && (irq_status & SPI_INT_TXEI)) {
while (dws->tx < dws->tx_end)
if (irq_status & SPI_INT_TXEI) {
spi_mask_intr(dws, SPI_INT_TXEI);
left = (dws->tx_end - dws->tx) / dws->n_bytes;
left = (left > int_level) ? int_level : left;
while (left--)
dws->write(dws);
dws->read(dws);
if (dws->tx == dws->tx_end) {
spi_mask_intr(dws, SPI_INT_TXEI);
transfer_complete(dws);
}
}
/* INT comes from rx */
if (dws->rx && (irq_status & SPI_INT_RXFI)) {
if (dws->read(dws))
/* Re-enable the IRQ if there is still data left to tx */
if (dws->tx_end > dws->tx)
spi_umask_intr(dws, SPI_INT_TXEI);
else
transfer_complete(dws);
}
return IRQ_HANDLED;
}
@ -428,6 +431,7 @@ static void pump_transfers(unsigned long data)
u8 bits = 0;
u8 imask = 0;
u8 cs_change = 0;
u16 txint_level = 0;
u16 clk_div = 0;
u32 speed = 0;
u32 cr0 = 0;
@ -438,6 +442,9 @@ static void pump_transfers(unsigned long data)
chip = dws->cur_chip;
spi = message->spi;
if (unlikely(!chip->clk_div))
chip->clk_div = dws->max_freq / chip->speed_hz;
if (message->state == ERROR_STATE) {
message->status = -EIO;
goto early_exit;
@ -492,7 +499,7 @@ static void pump_transfers(unsigned long data)
/* clk_div doesn't support odd number */
clk_div = dws->max_freq / speed;
clk_div = (clk_div >> 1) << 1;
clk_div = (clk_div + 1) & 0xfffe;
chip->speed_hz = speed;
chip->clk_div = clk_div;
@ -535,11 +542,16 @@ static void pump_transfers(unsigned long data)
/* Check if current transfer is a DMA transaction */
dws->dma_mapped = map_dma_buffers(dws);
/*
* Interrupt mode
* we only need set the TXEI IRQ, as TX/RX always happen syncronizely
*/
if (!dws->dma_mapped && !chip->poll_mode) {
if (dws->rx)
imask |= SPI_INT_RXFI;
if (dws->tx)
imask |= SPI_INT_TXEI;
int templen = dws->len / dws->n_bytes;
txint_level = dws->fifo_len / 2;
txint_level = (templen > txint_level) ? txint_level : templen;
imask |= SPI_INT_TXEI;
dws->transfer_handler = interrupt_transfer;
}
@ -549,21 +561,23 @@ static void pump_transfers(unsigned long data)
* 2. clk_div is changed
* 3. control value changes
*/
if (dw_readw(dws, ctrl0) != cr0 || cs_change || clk_div) {
if (dw_readw(dws, ctrl0) != cr0 || cs_change || clk_div || imask) {
spi_enable_chip(dws, 0);
if (dw_readw(dws, ctrl0) != cr0)
dw_writew(dws, ctrl0, cr0);
/* Set the interrupt mask, for poll mode just diable all int */
spi_mask_intr(dws, 0xff);
if (!chip->poll_mode)
spi_umask_intr(dws, imask);
spi_set_clk(dws, clk_div ? clk_div : chip->clk_div);
spi_chip_sel(dws, spi->chip_select);
spi_enable_chip(dws, 1);
/* Set the interrupt mask, for poll mode just diable all int */
spi_mask_intr(dws, 0xff);
if (imask)
spi_umask_intr(dws, imask);
if (txint_level)
dw_writew(dws, txfltr, txint_level);
spi_enable_chip(dws, 1);
if (cs_change)
dws->prev_chip = chip;
}
@ -712,11 +726,11 @@ static int dw_spi_setup(struct spi_device *spi)
}
chip->bits_per_word = spi->bits_per_word;
if (!spi->max_speed_hz) {
dev_err(&spi->dev, "No max speed HZ parameter\n");
return -EINVAL;
}
chip->speed_hz = spi->max_speed_hz;
if (chip->speed_hz)
chip->clk_div = 25000000 / chip->speed_hz;
else
chip->clk_div = 8; /* default value */
chip->tmode = 0; /* Tx & Rx */
/* Default SPI mode is SCPOL = 0, SCPH = 0 */

1
drivers/spi/dw_spi_pci.c
View File

@ -73,6 +73,7 @@ static int __devinit spi_pci_probe(struct pci_dev *pdev,
dws->num_cs = 4;
dws->max_freq = 25000000; /* for Moorestwon */
dws->irq = pdev->irq;
dws->fifo_len = 40; /* FIFO has 40 words buffer */
ret = dw_spi_add_host(dws);
if (ret)

1
include/linux/spi/dw_spi.h
View File

@ -90,6 +90,7 @@ struct dw_spi {
unsigned long paddr;
u32 iolen;
int irq;
u32 fifo_len; /* depth of the FIFO buffer */
u32 max_freq; /* max bus freq supported */
u16 bus_num;