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Subject[PATCH 08/11] spi: pxa2xx: Add slave mode support
Date
Tested on an OLPC XO-1.75 machine, where the Embedded Controller happens
to be a SPI master.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
---
drivers/spi/spi-pxa2xx.c | 81 +++++++++++++++++++++++++++++++---
include/linux/spi/pxa2xx_spi.h | 1 +
2 files changed, 75 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 58554c765a87..3848842d68fd 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -626,6 +626,11 @@ static irqreturn_t interrupt_transfer(struct driver_data *drv_data)
return IRQ_HANDLED;
}

+ if (irq_status & SSSR_TUR) {
+ int_error_stop(drv_data, "interrupt_transfer: fifo underrun");
+ return IRQ_HANDLED;
+ }
+
if (irq_status & SSSR_TINT) {
pxa2xx_spi_write(drv_data, SSSR, SSSR_TINT);
if (drv_data->read(drv_data)) {
@@ -1071,6 +1076,11 @@ static int pxa2xx_spi_transfer_one(struct spi_controller *master,
pxa2xx_spi_write(drv_data, SSTO, chip->timeout);
}

+ if (spi_controller_is_slave(master)) {
+ while (drv_data->write(drv_data))
+ ;
+ }
+
/*
* Release the data by enabling service requests and interrupts,
* without changing any mode bits
@@ -1080,6 +1090,27 @@ static int pxa2xx_spi_transfer_one(struct spi_controller *master,
return 1;
}

+static int pxa2xx_spi_slave_abort(struct spi_master *master)
+{
+ struct driver_data *drv_data = spi_controller_get_devdata(master);
+
+ /* Stop and reset SSP */
+ write_SSSR_CS(drv_data, drv_data->clear_sr);
+ reset_sccr1(drv_data);
+ if (!pxa25x_ssp_comp(drv_data))
+ pxa2xx_spi_write(drv_data, SSTO, 0);
+ pxa2xx_spi_flush(drv_data);
+ pxa2xx_spi_write(drv_data, SSCR0,
+ pxa2xx_spi_read(drv_data, SSCR0) & ~SSCR0_SSE);
+
+ dev_dbg(&drv_data->pdev->dev, "transfer aborted\n");
+
+ drv_data->master->cur_msg->status = -EINTR;
+ spi_finalize_current_transfer(drv_data->master);
+
+ return 0;
+}
+
static void pxa2xx_spi_handle_err(struct spi_controller *master,
struct spi_message *msg)
{
@@ -1207,9 +1238,14 @@ static int setup(struct spi_device *spi)
rx_thres = config->rx_threshold;
break;
default:
- tx_thres = TX_THRESH_DFLT;
tx_hi_thres = 0;
- rx_thres = RX_THRESH_DFLT;
+ if (spi_controller_is_slave(drv_data->master)) {
+ tx_thres = 1;
+ rx_thres = 2;
+ } else {
+ tx_thres = TX_THRESH_DFLT;
+ rx_thres = RX_THRESH_DFLT;
+ }
break;
}

@@ -1253,6 +1289,12 @@ static int setup(struct spi_device *spi)
if (chip_info->enable_loopback)
chip->cr1 = SSCR1_LBM;
}
+ if (spi_controller_is_slave(drv_data->master)) {
+ chip->cr1 |= SSCR1_SCFR;
+ chip->cr1 |= SSCR1_SCLKDIR;
+ chip->cr1 |= SSCR1_SFRMDIR;
+ chip->cr1 |= SSCR1_SPH;
+ }

chip->lpss_rx_threshold = SSIRF_RxThresh(rx_thres);
chip->lpss_tx_threshold = SSITF_TxLoThresh(tx_thres)
@@ -1492,6 +1534,13 @@ pxa2xx_spi_init_pdata(struct platform_device *pdev)
}
#endif

+#if CONFIG_OF
+ if (of_id) {
+ pdata->is_slave = of_property_read_bool(pdev->dev.of_node,
+ "spi-slave");
+ }
+#endif
+
ssp->clk = devm_clk_get(&pdev->dev, NULL);
ssp->irq = platform_get_irq(pdev, 0);
ssp->type = type;
@@ -1557,7 +1606,11 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
return -ENODEV;
}

- master = spi_alloc_master(dev, sizeof(struct driver_data));
+ if (platform_info->is_slave)
+ master = spi_alloc_slave(dev, sizeof(struct driver_data));
+ else
+ master = spi_alloc_master(dev, sizeof(struct driver_data));
+
if (!master) {
dev_err(&pdev->dev, "cannot alloc spi_master\n");
pxa_ssp_free(ssp);
@@ -1579,6 +1632,7 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
master->setup = setup;
master->set_cs = pxa2xx_spi_set_cs;
master->transfer_one = pxa2xx_spi_transfer_one;
+ master->slave_abort = pxa2xx_spi_slave_abort;
master->handle_err = pxa2xx_spi_handle_err;
master->unprepare_transfer_hardware = pxa2xx_spi_unprepare_transfer;
master->fw_translate_cs = pxa2xx_spi_fw_translate_cs;
@@ -1608,7 +1662,8 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
drv_data->int_cr1 = SSCR1_TIE | SSCR1_RIE | SSCR1_TINTE;
drv_data->dma_cr1 = DEFAULT_DMA_CR1;
drv_data->clear_sr = SSSR_ROR | SSSR_TINT;
- drv_data->mask_sr = SSSR_TINT | SSSR_RFS | SSSR_TFS | SSSR_ROR;
+ drv_data->mask_sr = SSSR_TINT | SSSR_RFS | SSSR_TFS
+ | SSSR_ROR | SSSR_TUR;
}

status = request_irq(ssp->irq, ssp_int, IRQF_SHARED, dev_name(dev),
@@ -1656,10 +1711,22 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
pxa2xx_spi_write(drv_data, SSCR0, tmp);
break;
default:
- tmp = SSCR1_RxTresh(RX_THRESH_DFLT) |
- SSCR1_TxTresh(TX_THRESH_DFLT);
+
+ if (spi_controller_is_slave(master)) {
+ tmp = SSCR1_SCFR |
+ SSCR1_SCLKDIR |
+ SSCR1_SFRMDIR |
+ SSCR1_RxTresh(2) |
+ SSCR1_TxTresh(1) |
+ SSCR1_SPH;
+ } else {
+ tmp = SSCR1_RxTresh(RX_THRESH_DFLT) |
+ SSCR1_TxTresh(TX_THRESH_DFLT);
+ }
pxa2xx_spi_write(drv_data, SSCR1, tmp);
- tmp = SSCR0_SCR(2) | SSCR0_Motorola | SSCR0_DataSize(8);
+ tmp = SSCR0_Motorola | SSCR0_DataSize(8);
+ if (!spi_controller_is_slave(master))
+ tmp |= SSCR0_SCR(2);
pxa2xx_spi_write(drv_data, SSCR0, tmp);
break;
}
diff --git a/include/linux/spi/pxa2xx_spi.h b/include/linux/spi/pxa2xx_spi.h
index 9ec4c147abbc..b0674e330ef6 100644
--- a/include/linux/spi/pxa2xx_spi.h
+++ b/include/linux/spi/pxa2xx_spi.h
@@ -25,6 +25,7 @@ struct dma_chan;
struct pxa2xx_spi_master {
u16 num_chipselect;
u8 enable_dma;
+ bool is_slave;

/* DMA engine specific config */
bool (*dma_filter)(struct dma_chan *chan, void *param);
--
2.19.0
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