[PATCH v0 1/1] spi: spi-rockchip: add support for spi slave_mode

[Chris Ruehl <chris.ruehl@gtsys.com.hk>]

This patch aim to add spi slave mode support to the rockchip driver.
Fix the wrong usage of num_cs set fix to ROCKCHIP_SPI_MAX_CS_NUM,
instead use max_native_cs flag to set the limit of native chip-select.
Enable use_gpio_descriptors to have cs_gpiod for gpio based chip-selects.

Signed-off-by: Chris Ruehl <chris.ruehl@gtsys.com.hk>
---
 drivers/spi/spi-rockchip.c | 46 +++++++++++++++++++++++++++++++++-----
 1 file changed, 41 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 70ef63e0b6b8..9c1ff52c0f85 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -183,6 +183,9 @@ struct rockchip_spi {
 	u8 rsd;
 
 	bool cs_asserted[ROCKCHIP_SPI_MAX_CS_NUM];
+
+	bool slave_mode;
+	bool slave_abort;
 };
 
 static inline void spi_enable_chip(struct rockchip_spi *rs, bool enable)
@@ -359,7 +362,7 @@ static void rockchip_spi_dma_rxcb(void *data)
 	struct rockchip_spi *rs = spi_master_get_devdata(master);
 	int state = atomic_fetch_andnot(RXDMA, &rs->state);
 
-	if (state & TXDMA)
+	if (state & TXDMA && !rs->slave_abort)
 		return;
 
 	spi_enable_chip(rs, false);
@@ -372,7 +375,7 @@ static void rockchip_spi_dma_txcb(void *data)
 	struct rockchip_spi *rs = spi_master_get_devdata(master);
 	int state = atomic_fetch_andnot(TXDMA, &rs->state);
 
-	if (state & RXDMA)
+	if (state & RXDMA && !rs->slave_abort)
 		return;
 
 	/* Wait until the FIFO data completely. */
@@ -466,6 +469,10 @@ static void rockchip_spi_config(struct rockchip_spi *rs,
 	u32 cr1;
 	u32 dmacr = 0;
 
+	if (rs->slavemode)
+		cr0 |= CR0_OPM_SLAVE << CR0_OPM_OFFSET;
+	rs->slave_abort = false;
+
 	cr0 |= rs->rsd << CR0_RSD_OFFSET;
 	cr0 |= (spi->mode & 0x3U) << CR0_SCPH_OFFSET;
 	if (spi->mode & SPI_LSB_FIRST)
@@ -535,6 +542,16 @@ static size_t rockchip_spi_max_transfer_size(struct spi_device *spi)
 	return ROCKCHIP_SPI_MAX_TRANLEN;
 }
 
+static int rockchip_spi_slave_abort(struct spi_master *master)
+{
+	struct rockchip_spi *rs = spi_master_get_devdata(master);
+
+	rs->slave_abort = true;
+	complete(master);
+
+	return 0;
+}
+
 static int rockchip_spi_transfer_one(
 		struct spi_master *master,
 		struct spi_device *spi,
@@ -589,14 +606,25 @@ static int rockchip_spi_probe(struct platform_device *pdev)
 	struct spi_master *master;
 	struct resource *mem;
 	u32 rsd_nsecs;
+	bool slave_mode;
+	u32 num_cs = 1;
+
+	slave_mode = of_property_read_bool(np, "spi-slave");
+
+	if (slave_mode)
+		master = spi_alloc_slave(&pdev->dev,
+				sizeof(struct rockchip_spi));
+	else
+		master = spi_alloc_master(&pdev->dev,
+				sizeof(struct rockchip_spi));
 
-	master = spi_alloc_master(&pdev->dev, sizeof(struct rockchip_spi));
 	if (!master)
 		return -ENOMEM;
 
 	platform_set_drvdata(pdev, master);
 
 	rs = spi_master_get_devdata(master);
+	rs->slave_mode = slave_mode;
 
 	/* Get basic io resource and map it */
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -676,7 +704,16 @@ static int rockchip_spi_probe(struct platform_device *pdev)
 	master->auto_runtime_pm = true;
 	master->bus_num = pdev->id;
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP | SPI_LSB_FIRST;
-	master->num_chipselect = ROCKCHIP_SPI_MAX_CS_NUM;
+	if (slave_mode) {
+		master->mode_bits |= SPI_NO_CS;
+		master->slave_abort = rockchip_spi_slave_abort;
+	} else {
+		of_property_read_u32(np, "num-cs", &num_cs);
+		master->num_chipselect = num_cs;
+		master->use_gpio_descriptors = true;
+		master->max_native_cs = ROCKCHIP_SPI_MAX_CS_NUM;
+		master->flags = SPI_MASTER_GPIO_SS;
+	}
 	master->dev.of_node = pdev->dev.of_node;
 	master->bits_per_word_mask = SPI_BPW_MASK(16) | SPI_BPW_MASK(8) | SPI_BPW_MASK(4);
 	master->min_speed_hz = rs->freq / BAUDR_SCKDV_MAX;
@@ -686,7 +723,6 @@ static int rockchip_spi_probe(struct platform_device *pdev)
 	master->transfer_one = rockchip_spi_transfer_one;
 	master->max_transfer_size = rockchip_spi_max_transfer_size;
 	master->handle_err = rockchip_spi_handle_err;
-	master->flags = SPI_MASTER_GPIO_SS;
 
 	master->dma_tx = dma_request_chan(rs->dev, "tx");
 	if (IS_ERR(master->dma_tx)) {
-- 
2.20.1