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Unverified Commit bcd87317 authored by Clark Wang's avatar Clark Wang Committed by Mark Brown
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spi: lpspi: Add slave mode support 



Add slave mode support to the fsl-lpspi driver, only in PIO mode.

For now, there are some limitations for slave mode transmission:
1. The stale data in RXFIFO will be dropped when the Slave does any new
   transfer.
2. One transfer can be finished only after all transfer->len data been
   transferred to master device
3. Slave device only accepts transfer->len data. Any data longer than
   this from master device will be dropped. Any data shorter than this
   from master will cause LPSPI to stuck due to mentioned limitation 2.
4. Only PIO transfer is supported in Slave Mode.

Wire connection:
GND, SCK, MISO(to MISO of slave), MOSI(to MOSI of slave), SCS

Signed-off-by: default avatarClark Wang <xiaoning.wang@nxp.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 07d71557

drivers/spi/spi-fsl-lpspi.c

+79 −28
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ 
#define IER_RDIE	BIT(1)

#define IER_TDIE	BIT(0)

#define CFGR1_PCSCFG	BIT(27)

#define CFGR1_PINCFG	(BIT(24)|BIT(25))

#define CFGR1_PCSPOL	BIT(8)

#define CFGR1_NOSTALL	BIT(3)

#define CFGR1_MASTER	BIT(0)
@@ -80,6 +81,7 @@ struct fsl_lpspi_data { 
	struct device *dev;

	void __iomem *base;

	struct clk *clk;

	bool is_slave;



	void *rx_buf;

	const void *tx_buf;
@@ -92,6 +94,8 @@ struct fsl_lpspi_data { 


	struct lpspi_config config;

	struct completion xfer_done;



	bool slave_aborted;

};



static const struct of_device_id fsl_lpspi_dt_ids[] = {
@@ -206,8 +210,9 @@ static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi, 
	u32 temp = 0;



	temp |= fsl_lpspi->config.bpw - 1;

	temp |= fsl_lpspi->config.prescale << 27;

	temp |= (fsl_lpspi->config.mode & 0x3) << 30;

	if (!fsl_lpspi->is_slave) {

		temp |= fsl_lpspi->config.prescale << 27;

		temp |= (fsl_lpspi->config.chip_select & 0x3) << 24;



		/*
@@ -220,7 +225,7 @@ static void fsl_lpspi_set_cmd(struct fsl_lpspi_data *fsl_lpspi, 
			temp &= ~TCR_CONTC;

		else

			temp |= TCR_CONTC;



	}

	writel(temp, fsl_lpspi->base + IMX7ULP_TCR);



	dev_dbg(fsl_lpspi->dev, "TCR=0x%x\n", temp);
@@ -273,13 +278,18 @@ static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi) 
	writel(temp, fsl_lpspi->base + IMX7ULP_CR);

	writel(0, fsl_lpspi->base + IMX7ULP_CR);



	if (!fsl_lpspi->is_slave) {

		ret = fsl_lpspi_set_bitrate(fsl_lpspi);

		if (ret)

			return ret;

	}



	fsl_lpspi_set_watermark(fsl_lpspi);



	temp = CFGR1_PCSCFG | CFGR1_MASTER;

	if (!fsl_lpspi->is_slave)

		temp = CFGR1_MASTER;

	else

		temp = CFGR1_PINCFG;

	if (fsl_lpspi->config.mode & SPI_CS_HIGH)

		temp |= CFGR1_PCSPOL;

	writel(temp, fsl_lpspi->base + IMX7ULP_CFGR1);
@@ -322,6 +332,37 @@ static void fsl_lpspi_setup_transfer(struct spi_device *spi, 
	fsl_lpspi_config(fsl_lpspi);

}



static int fsl_lpspi_slave_abort(struct spi_controller *controller)

{

	struct fsl_lpspi_data *fsl_lpspi =

				spi_controller_get_devdata(controller);



	fsl_lpspi->slave_aborted = true;

	complete(&fsl_lpspi->xfer_done);

	return 0;

}



static int fsl_lpspi_wait_for_completion(struct spi_controller *controller)

{

	struct fsl_lpspi_data *fsl_lpspi =

				spi_controller_get_devdata(controller);



	if (fsl_lpspi->is_slave) {

		if (wait_for_completion_interruptible(&fsl_lpspi->xfer_done) ||

			fsl_lpspi->slave_aborted) {

			dev_dbg(fsl_lpspi->dev, "interrupted\n");

			return -EINTR;

		}

	} else {

		if (!wait_for_completion_timeout(&fsl_lpspi->xfer_done, HZ)) {

			dev_dbg(fsl_lpspi->dev, "wait for completion timeout\n");

			return -ETIMEDOUT;

		}

	}



	return 0;

}



static int fsl_lpspi_transfer_one(struct spi_controller *controller,

				  struct spi_device *spi,

				  struct spi_transfer *t)
@@ -335,13 +376,13 @@ static int fsl_lpspi_transfer_one(struct spi_controller *controller, 
	fsl_lpspi->remain = t->len;



	reinit_completion(&fsl_lpspi->xfer_done);

	fsl_lpspi->slave_aborted = false;



	fsl_lpspi_write_tx_fifo(fsl_lpspi);



	ret = wait_for_completion_timeout(&fsl_lpspi->xfer_done, HZ);

	if (!ret) {

		dev_dbg(fsl_lpspi->dev, "wait for completion timeout\n");

		return -ETIMEDOUT;

	}

	ret = fsl_lpspi_wait_for_completion(controller);

	if (ret)

		return ret;



	ret = fsl_lpspi_txfifo_empty(fsl_lpspi);

	if (ret)
@@ -380,10 +421,12 @@ static int fsl_lpspi_transfer_one_msg(struct spi_controller *controller, 
	}



complete:

	if (!fsl_lpspi->is_slave) {

		/* de-assert SS, then finalize current message */

		temp = readl(fsl_lpspi->base + IMX7ULP_TCR);

		temp &= ~TCR_CONTC;

		writel(temp, fsl_lpspi->base + IMX7ULP_TCR);

	}



	msg->status = ret;

	spi_finalize_current_message(controller);
@@ -421,8 +464,13 @@ static int fsl_lpspi_probe(struct platform_device *pdev) 
	int ret, irq;

	u32 temp;



	if (of_property_read_bool((&pdev->dev)->of_node, "spi-slave"))

		controller = spi_alloc_slave(&pdev->dev,

					sizeof(struct fsl_lpspi_data));

	else

		controller = spi_alloc_master(&pdev->dev,

					sizeof(struct fsl_lpspi_data));



	if (!controller)

		return -ENOMEM;
@@ -433,6 +481,8 @@ static int fsl_lpspi_probe(struct platform_device *pdev) 


	fsl_lpspi = spi_controller_get_devdata(controller);

	fsl_lpspi->dev = &pdev->dev;

	fsl_lpspi->is_slave = of_property_read_bool((&pdev->dev)->of_node,

						    "spi-slave");



	controller->transfer_one_message = fsl_lpspi_transfer_one_msg;

	controller->prepare_transfer_hardware = lpspi_prepare_xfer_hardware;
@@ -441,6 +491,7 @@ static int fsl_lpspi_probe(struct platform_device *pdev) 
	controller->flags = SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX;

	controller->dev.of_node = pdev->dev.of_node;

	controller->bus_num = pdev->id;

	controller->slave_abort = fsl_lpspi_slave_abort;



	init_completion(&fsl_lpspi->xfer_done);