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Commit f6f46de1 authored by Roland Stigge's avatar Roland Stigge Committed by Mark Brown
Browse files

spi/pl022: Add chip select handling via GPIO 



This patch adds the ability for the driver to control the chip select directly.
This enables independence from cs_control callbacks.  Configurable via
platform_data, to be extended as DT in the following patch.

Based on the initial patch by Alexandre Pereira da Silva <aletes.xgr@gmail.com>

Signed-off-by: default avatarRoland Stigge <stigge@antcom.de>
Acked-by: default avatarAlexandre Pereira da Silva <aletes.xgr@gmail.com>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
parent 3ce8859e

drivers/spi/spi-pl022.c

+34 −14
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ 
#include <linux/dma-mapping.h>

#include <linux/scatterlist.h>

#include <linux/pm_runtime.h>

#include <linux/gpio.h>



/*

 * This macro is used to define some register default values.
@@ -356,6 +357,8 @@ struct vendor_data { 
 * @sgt_rx: scattertable for the RX transfer

 * @sgt_tx: scattertable for the TX transfer

 * @dummypage: a dummy page used for driving data on the bus with DMA

 * @cur_cs: current chip select (gpio)

 * @chipselects: list of chipselects (gpios)

 */

struct pl022 {

	struct amba_device		*adev;
@@ -389,6 +392,8 @@ struct pl022 { 
	char				*dummypage;

	bool				dma_running;

#endif

	int cur_cs;

	int *chipselects;

};



/**
@@ -433,6 +438,14 @@ static void null_cs_control(u32 command) 
	pr_debug("pl022: dummy chip select control, CS=0x%x\n", command);

}



static void pl022_cs_control(struct pl022 *pl022, u32 command)

{

	if (gpio_is_valid(pl022->cur_cs))

		gpio_set_value(pl022->cur_cs, command);

	else

		pl022->cur_chip->cs_control(command);

}



/**

 * giveback - current spi_message is over, schedule next message and call

 * callback of this message. Assumes that caller already
@@ -479,7 +492,7 @@ static void giveback(struct pl022 *pl022) 
		if (next_msg && next_msg->spi != pl022->cur_msg->spi)

			next_msg = NULL;

		if (!next_msg || pl022->cur_msg->state == STATE_ERROR)

			pl022->cur_chip->cs_control(SSP_CHIP_DESELECT);

			pl022_cs_control(pl022, SSP_CHIP_DESELECT);

		else

			pl022->next_msg_cs_active = true;
@@ -818,8 +831,7 @@ static void dma_callback(void *data) 
	/* Update total bytes transferred */

	msg->actual_length += pl022->cur_transfer->len;

	if (pl022->cur_transfer->cs_change)

		pl022->cur_chip->

			cs_control(SSP_CHIP_DESELECT);

		pl022_cs_control(pl022, SSP_CHIP_DESELECT);



	/* Move to next transfer */

	msg->state = next_transfer(pl022);
@@ -1252,8 +1264,7 @@ static irqreturn_t pl022_interrupt_handler(int irq, void *dev_id) 
		/* Update total bytes transferred */

		msg->actual_length += pl022->cur_transfer->len;

		if (pl022->cur_transfer->cs_change)

			pl022->cur_chip->

				cs_control(SSP_CHIP_DESELECT);

			pl022_cs_control(pl022, SSP_CHIP_DESELECT);

		/* Move to next transfer */

		msg->state = next_transfer(pl022);

		tasklet_schedule(&pl022->pump_transfers);
@@ -1338,7 +1349,7 @@ static void pump_transfers(unsigned long data) 


		/* Reselect chip select only if cs_change was requested */

		if (previous->cs_change)

			pl022->cur_chip->cs_control(SSP_CHIP_SELECT);

			pl022_cs_control(pl022, SSP_CHIP_SELECT);

	} else {

		/* STATE_START */

		message->state = STATE_RUNNING;
@@ -1377,7 +1388,7 @@ static void do_interrupt_dma_transfer(struct pl022 *pl022) 


	/* Enable target chip, if not already active */

	if (!pl022->next_msg_cs_active)

		pl022->cur_chip->cs_control(SSP_CHIP_SELECT);

		pl022_cs_control(pl022, SSP_CHIP_SELECT);



	if (set_up_next_transfer(pl022, pl022->cur_transfer)) {

		/* Error path */
@@ -1429,12 +1440,12 @@ static void do_polling_transfer(struct pl022 *pl022) 
			if (previous->delay_usecs)

				udelay(previous->delay_usecs);

			if (previous->cs_change)

				pl022->cur_chip->cs_control(SSP_CHIP_SELECT);

				pl022_cs_control(pl022, SSP_CHIP_SELECT);

		} else {

			/* STATE_START */

			message->state = STATE_RUNNING;

			if (!pl022->next_msg_cs_active)

				pl022->cur_chip->cs_control(SSP_CHIP_SELECT);

				pl022_cs_control(pl022, SSP_CHIP_SELECT);

		}



		/* Configuration Changing Per Transfer */
@@ -1466,7 +1477,7 @@ static void do_polling_transfer(struct pl022 *pl022) 
		/* Update total byte transferred */

		message->actual_length += pl022->cur_transfer->len;

		if (pl022->cur_transfer->cs_change)

			pl022->cur_chip->cs_control(SSP_CHIP_DESELECT);

			pl022_cs_control(pl022, SSP_CHIP_DESELECT);

		/* Move to next transfer */

		message->state = next_transfer(pl022);

	}
@@ -1495,6 +1506,7 @@ static int pl022_transfer_one_message(struct spi_master *master, 


	/* Setup the SPI using the per chip configuration */

	pl022->cur_chip = spi_get_ctldata(msg->spi);

	pl022->cur_cs = pl022->chipselects[msg->spi->chip_select];



	restore_state(pl022);

	flush(pl022);
@@ -1840,8 +1852,9 @@ static int pl022_setup(struct spi_device *spi) 
	chip->xfer_type = chip_info->com_mode;

	if (!chip_info->cs_control) {

		chip->cs_control = null_cs_control;

		if (!gpio_is_valid(pl022->chipselects[spi->chip_select]))

			dev_warn(&spi->dev,

			 "chip select function is NULL for this chip\n");

				 "invalid chip select\n");

	} else

		chip->cs_control = chip_info->cs_control;
@@ -1993,7 +2006,7 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id) 
	struct pl022_ssp_controller *platform_info = adev->dev.platform_data;

	struct spi_master *master;

	struct pl022 *pl022 = NULL;	/*Data for this driver */

	int status = 0;

	int status = 0, i;



	dev_info(&adev->dev,

		 "ARM PL022 driver, device ID: 0x%08x\n", adev->periphid);
@@ -2004,7 +2017,8 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id) 
	}



	/* Allocate master with space for data */

	master = spi_alloc_master(dev, sizeof(struct pl022));

	master = spi_alloc_master(dev, sizeof(struct pl022) + sizeof(int) *

				  platform_info->num_chipselect);

	if (master == NULL) {

		dev_err(&adev->dev, "probe - cannot alloc SPI master\n");

		status = -ENOMEM;
@@ -2016,6 +2030,8 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id) 
	pl022->master_info = platform_info;

	pl022->adev = adev;

	pl022->vendor = id->data;

	/* Point chipselects to allocated memory beyond the main struct */

	pl022->chipselects = (int *) pl022 + sizeof(struct pl022);



	/*

	 * Bus Number Which has been Assigned to this SSP controller
@@ -2030,6 +2046,10 @@ pl022_probe(struct amba_device *adev, const struct amba_id *id) 
	master->unprepare_transfer_hardware = pl022_unprepare_transfer_hardware;

	master->rt = platform_info->rt;



	if (platform_info->num_chipselect && platform_info->chipselects)

		for (i = 0; i < platform_info->num_chipselect; i++)

			pl022->chipselects[i] = platform_info->chipselects[i];



	/*

	 * Supports mode 0-3, loopback, and active low CS. Transfers are

	 * always MS bit first on the original pl022.

include/linux/amba/pl022.h

+2 −0
Original line number Diff line number Diff line
@@ -244,6 +244,7 @@ struct dma_chan; 
 *     indicates no delay and the device will be suspended immediately.

 * @rt: indicates the controller should run the message pump with realtime

 *     priority to minimise the transfer latency on the bus.

 * @chipselects: list of <num_chipselects> chip select gpios

 */

struct pl022_ssp_controller {

	u16 bus_id;
@@ -254,6 +255,7 @@ struct pl022_ssp_controller { 
	void *dma_tx_param;

	int autosuspend_delay;

	bool rt;

	int *chipselects;

};



/**