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spi/pl022: Add chip select handling via GPIO
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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: Roland Stigge <stigge@antcom.de>
Acked-by: Alexandre Pereira da Silva <aletes.xgr@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
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Roland Stigge authored and Mark Brown committed Aug 22, 2012
1 parent 3ce8859 commit f6f46de
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Showing 2 changed files with 36 additions and 14 deletions.
48 changes: 34 additions & 14 deletions drivers/spi/spi-pl022.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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.
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -389,6 +392,8 @@ struct pl022 {
char *dummypage;
bool dma_running;
#endif
int cur_cs;
int *chipselects;
};

/**
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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);
}
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
dev_warn(&spi->dev,
"chip select function is NULL for this chip\n");
if (!gpio_is_valid(pl022->chipselects[spi->chip_select]))
dev_warn(&spi->dev,
"invalid chip select\n");
} else
chip->cs_control = chip_info->cs_control;

Expand Down Expand Up @@ -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);
Expand All @@ -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;
Expand All @@ -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
Expand All @@ -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.
Expand Down
2 changes: 2 additions & 0 deletions include/linux/amba/pl022.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -254,6 +255,7 @@ struct pl022_ssp_controller {
void *dma_tx_param;
int autosuspend_delay;
bool rt;
int *chipselects;
};

/**
Expand Down

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