spi/bfin_spi: utilize the SPI interrupt in PIO mode
The current behavior in PIO mode is to poll the SPI status registers which
can obviously lead to higher latencies when doing a lot of SPI traffic.
There is a SPI interrupt which can be used instead to signal individual
completion of transactions.
Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index b835254..3736c35 100644
--- a/drivers/spi/spi_bfin5xx.c
+++ b/drivers/spi/spi_bfin5xx.c
@@ -92,6 +92,9 @@
dma_addr_t rx_dma;
dma_addr_t tx_dma;
+ int irq_requested;
+ int spi_irq;
+
size_t rx_map_len;
size_t tx_map_len;
u8 n_bytes;
@@ -115,6 +118,7 @@
u16 cs_chg_udelay; /* Some devices require > 255usec delay */
u32 cs_gpio;
u16 idle_tx_val;
+ u8 pio_interrupt; /* use spi data irq */
void (*write) (struct driver_data *);
void (*read) (struct driver_data *);
void (*duplex) (struct driver_data *);
@@ -525,6 +529,79 @@
msg->complete(msg->context);
}
+/* spi data irq handler */
+static irqreturn_t bfin_spi_pio_irq_handler(int irq, void *dev_id)
+{
+ struct driver_data *drv_data = dev_id;
+ struct chip_data *chip = drv_data->cur_chip;
+ struct spi_message *msg = drv_data->cur_msg;
+ int n_bytes = drv_data->n_bytes;
+
+ /* wait until transfer finished. */
+ while (!(read_STAT(drv_data) & BIT_STAT_RXS))
+ cpu_relax();
+
+ if ((drv_data->tx && drv_data->tx >= drv_data->tx_end) ||
+ (drv_data->rx && drv_data->rx >= (drv_data->rx_end - n_bytes))) {
+ /* last read */
+ if (drv_data->rx) {
+ dev_dbg(&drv_data->pdev->dev, "last read\n");
+ if (n_bytes == 2)
+ *(u16 *) (drv_data->rx) = read_RDBR(drv_data);
+ else if (n_bytes == 1)
+ *(u8 *) (drv_data->rx) = read_RDBR(drv_data);
+ drv_data->rx += n_bytes;
+ }
+
+ msg->actual_length += drv_data->len_in_bytes;
+ if (drv_data->cs_change)
+ bfin_spi_cs_deactive(drv_data, chip);
+ /* Move to next transfer */
+ msg->state = bfin_spi_next_transfer(drv_data);
+
+ disable_irq(drv_data->spi_irq);
+
+ /* Schedule transfer tasklet */
+ tasklet_schedule(&drv_data->pump_transfers);
+ return IRQ_HANDLED;
+ }
+
+ if (drv_data->rx && drv_data->tx) {
+ /* duplex */
+ dev_dbg(&drv_data->pdev->dev, "duplex: write_TDBR\n");
+ if (drv_data->n_bytes == 2) {
+ *(u16 *) (drv_data->rx) = read_RDBR(drv_data);
+ write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
+ } else if (drv_data->n_bytes == 1) {
+ *(u8 *) (drv_data->rx) = read_RDBR(drv_data);
+ write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
+ }
+ } else if (drv_data->rx) {
+ /* read */
+ dev_dbg(&drv_data->pdev->dev, "read: write_TDBR\n");
+ if (drv_data->n_bytes == 2)
+ *(u16 *) (drv_data->rx) = read_RDBR(drv_data);
+ else if (drv_data->n_bytes == 1)
+ *(u8 *) (drv_data->rx) = read_RDBR(drv_data);
+ write_TDBR(drv_data, chip->idle_tx_val);
+ } else if (drv_data->tx) {
+ /* write */
+ dev_dbg(&drv_data->pdev->dev, "write: write_TDBR\n");
+ bfin_spi_dummy_read(drv_data);
+ if (drv_data->n_bytes == 2)
+ write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
+ else if (drv_data->n_bytes == 1)
+ write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
+ }
+
+ if (drv_data->tx)
+ drv_data->tx += n_bytes;
+ if (drv_data->rx)
+ drv_data->rx += n_bytes;
+
+ return IRQ_HANDLED;
+}
+
static irqreturn_t bfin_spi_dma_irq_handler(int irq, void *dev_id)
{
struct driver_data *drv_data = dev_id;
@@ -700,6 +777,7 @@
default:
/* No change, the same as default setting */
+ transfer->bits_per_word = chip->bits_per_word;
drv_data->n_bytes = chip->n_bytes;
width = chip->width;
drv_data->write = drv_data->tx ? chip->write : bfin_spi_null_writer;
@@ -842,60 +920,86 @@
dma_enable_irq(drv_data->dma_channel);
local_irq_restore(flags);
- } else {
- /* IO mode write then read */
- dev_dbg(&drv_data->pdev->dev, "doing IO transfer\n");
+ return;
+ }
- /* we always use SPI_WRITE mode. SPI_READ mode
- seems to have problems with setting up the
- output value in TDBR prior to the transfer. */
+ if (chip->pio_interrupt) {
+ /* use write mode. spi irq should have been disabled */
+ cr = (read_CTRL(drv_data) & (~BIT_CTL_TIMOD));
write_CTRL(drv_data, (cr | CFG_SPI_WRITE));
- if (full_duplex) {
- /* full duplex mode */
- BUG_ON((drv_data->tx_end - drv_data->tx) !=
- (drv_data->rx_end - drv_data->rx));
- dev_dbg(&drv_data->pdev->dev,
- "IO duplex: cr is 0x%x\n", cr);
+ /* discard old RX data and clear RXS */
+ bfin_spi_dummy_read(drv_data);
- drv_data->duplex(drv_data);
-
- if (drv_data->tx != drv_data->tx_end)
- tranf_success = 0;
- } else if (drv_data->tx != NULL) {
- /* write only half duplex */
- dev_dbg(&drv_data->pdev->dev,
- "IO write: cr is 0x%x\n", cr);
-
- drv_data->write(drv_data);
-
- if (drv_data->tx != drv_data->tx_end)
- tranf_success = 0;
- } else if (drv_data->rx != NULL) {
- /* read only half duplex */
- dev_dbg(&drv_data->pdev->dev,
- "IO read: cr is 0x%x\n", cr);
-
- drv_data->read(drv_data);
- if (drv_data->rx != drv_data->rx_end)
- tranf_success = 0;
+ /* start transfer */
+ if (drv_data->tx == NULL)
+ write_TDBR(drv_data, chip->idle_tx_val);
+ else {
+ if (transfer->bits_per_word == 8)
+ write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
+ else if (transfer->bits_per_word == 16)
+ write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
+ drv_data->tx += drv_data->n_bytes;
}
- if (!tranf_success) {
- dev_dbg(&drv_data->pdev->dev,
- "IO write error!\n");
- message->state = ERROR_STATE;
- } else {
- /* Update total byte transfered */
- message->actual_length += drv_data->len_in_bytes;
- /* Move to next transfer of this msg */
- message->state = bfin_spi_next_transfer(drv_data);
- if (drv_data->cs_change)
- bfin_spi_cs_deactive(drv_data, chip);
- }
- /* Schedule next transfer tasklet */
- tasklet_schedule(&drv_data->pump_transfers);
+ /* once TDBR is empty, interrupt is triggered */
+ enable_irq(drv_data->spi_irq);
+ return;
}
+
+ /* IO mode */
+ dev_dbg(&drv_data->pdev->dev, "doing IO transfer\n");
+
+ /* we always use SPI_WRITE mode. SPI_READ mode
+ seems to have problems with setting up the
+ output value in TDBR prior to the transfer. */
+ write_CTRL(drv_data, (cr | CFG_SPI_WRITE));
+
+ if (full_duplex) {
+ /* full duplex mode */
+ BUG_ON((drv_data->tx_end - drv_data->tx) !=
+ (drv_data->rx_end - drv_data->rx));
+ dev_dbg(&drv_data->pdev->dev,
+ "IO duplex: cr is 0x%x\n", cr);
+
+ drv_data->duplex(drv_data);
+
+ if (drv_data->tx != drv_data->tx_end)
+ tranf_success = 0;
+ } else if (drv_data->tx != NULL) {
+ /* write only half duplex */
+ dev_dbg(&drv_data->pdev->dev,
+ "IO write: cr is 0x%x\n", cr);
+
+ drv_data->write(drv_data);
+
+ if (drv_data->tx != drv_data->tx_end)
+ tranf_success = 0;
+ } else if (drv_data->rx != NULL) {
+ /* read only half duplex */
+ dev_dbg(&drv_data->pdev->dev,
+ "IO read: cr is 0x%x\n", cr);
+
+ drv_data->read(drv_data);
+ if (drv_data->rx != drv_data->rx_end)
+ tranf_success = 0;
+ }
+
+ if (!tranf_success) {
+ dev_dbg(&drv_data->pdev->dev,
+ "IO write error!\n");
+ message->state = ERROR_STATE;
+ } else {
+ /* Update total byte transfered */
+ message->actual_length += drv_data->len_in_bytes;
+ /* Move to next transfer of this msg */
+ message->state = bfin_spi_next_transfer(drv_data);
+ if (drv_data->cs_change)
+ bfin_spi_cs_deactive(drv_data, chip);
+ }
+
+ /* Schedule next transfer tasklet */
+ tasklet_schedule(&drv_data->pump_transfers);
}
/* pop a msg from queue and kick off real transfer */
@@ -1047,6 +1151,7 @@
chip->cs_chg_udelay = chip_info->cs_chg_udelay;
chip->cs_gpio = chip_info->cs_gpio;
chip->idle_tx_val = chip_info->idle_tx_val;
+ chip->pio_interrupt = chip_info->pio_interrupt;
}
/* translate common spi framework into our register */
@@ -1096,6 +1201,11 @@
goto error;
}
+ if (chip->enable_dma && chip->pio_interrupt) {
+ dev_err(&spi->dev, "enable_dma is set, "
+ "do not set pio_interrupt\n");
+ goto error;
+ }
/*
* if any one SPI chip is registered and wants DMA, request the
* DMA channel for it
@@ -1119,6 +1229,18 @@
dma_disable_irq(drv_data->dma_channel);
}
+ if (chip->pio_interrupt && !drv_data->irq_requested) {
+ ret = request_irq(drv_data->spi_irq, bfin_spi_pio_irq_handler,
+ IRQF_DISABLED, "BFIN_SPI", drv_data);
+ if (ret) {
+ dev_err(&spi->dev, "Unable to register spi IRQ\n");
+ goto error;
+ }
+ drv_data->irq_requested = 1;
+ /* we use write mode, spi irq has to be disabled here */
+ disable_irq(drv_data->spi_irq);
+ }
+
if (chip->chip_select_num == 0) {
ret = gpio_request(chip->cs_gpio, spi->modalias);
if (ret) {
@@ -1328,11 +1450,19 @@
goto out_error_ioremap;
}
- drv_data->dma_channel = platform_get_irq(pdev, 0);
- if (drv_data->dma_channel < 0) {
+ res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
+ if (res == NULL) {
dev_err(dev, "No DMA channel specified\n");
status = -ENOENT;
- goto out_error_no_dma_ch;
+ goto out_error_free_io;
+ }
+ drv_data->dma_channel = res->start;
+
+ drv_data->spi_irq = platform_get_irq(pdev, 0);
+ if (drv_data->spi_irq < 0) {
+ dev_err(dev, "No spi pio irq specified\n");
+ status = -ENOENT;
+ goto out_error_free_io;
}
/* Initial and start queue */
@@ -1375,7 +1505,7 @@
out_error_queue_alloc:
bfin_spi_destroy_queue(drv_data);
-out_error_no_dma_ch:
+out_error_free_io:
iounmap((void *) drv_data->regs_base);
out_error_ioremap:
out_error_get_res:
@@ -1407,6 +1537,11 @@
free_dma(drv_data->dma_channel);
}
+ if (drv_data->irq_requested) {
+ free_irq(drv_data->spi_irq, drv_data);
+ drv_data->irq_requested = 0;
+ }
+
/* Disconnect from the SPI framework */
spi_unregister_master(drv_data->master);