LinuxLists.cc - [PATCH v5 1/2] spi/pl022: Add chip select handling via GPIO

2012-08-21 16:01:02

Subject: [PATCH v5 1/2] 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 <[email protected]>

Signed-off-by: Roland Stigge <[email protected]>
---
Applies to v3.6-rc2

Patch set changes since v4:
* Rename DT property: "pl022,num-chipselects" -> "num-cs"
* Removed reference to Linux code in DT binding documentation
* Removed property "pl022,hierarchy" - only support SPI master for now
* Documented DT property pl022,interface
* Removed property "pl022,slave-tx-disable" - not relevant in master mode
* Added kerneldoc for cur_cs and chipselect list
* Reorganized struct pl022 (int *chipselect)
* Introduced int *chipselects to struct pl022_ssp_controller
* Let platform data override DT data
* Split patches into CS handling vs. DT support

Changes since v3:
* Proper use of IS_ENABLED

Changes since v2:
* Use IS_ENABLED instead of #ifdef
* Remove bogus const change

Changes since v1:
* return EPROBE_DEFFER if gpios are not initialized yet

Thanks Thierry Reding, Rob Herring and Linus Walleij for reviewing!

drivers/spi/spi-pl022.c | 47 +++++++++++++++++++++++++++++++--------------
include/linux/amba/pl022.h | 2 +
2 files changed, 35 insertions(+), 14 deletions(-)

--- linux-2.6.orig/drivers/spi/spi-pl022.c
+++ linux-2.6/drivers/spi/spi-pl022.c
@@ -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)
+ * @chipselect: 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 *chipselect;
};

/**
@@ -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_handl
/* 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

/* 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(st

/* 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 p
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 p
/* 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(st

/* Setup the SPI using the per chip configuration */
pl022->cur_chip = spi_get_ctldata(msg->spi);
+ pl022->cur_cs = pl022->chipselect[msg->spi->chip_select];

restore_state(pl022);
flush(pl022);
@@ -1840,8 +1852,9 @@ static int pl022_setup(struct spi_device
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->chipselect[spi->chip_select]))
+ dev_warn(&spi->dev,
+ "chip select function is NULL for this chip\n");
} else
chip->cs_control = chip_info->cs_control;

@@ -1993,7 +2006,7 @@ pl022_probe(struct amba_device *adev, co
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, co
}

/* 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 +2030,7 @@ pl022_probe(struct amba_device *adev, co
pl022->master_info = platform_info;
pl022->adev = adev;
pl022->vendor = id->data;
+ pl022->chipselect = (int *)&master[1];

/*
* Bus Number Which has been Assigned to this SSP controller
@@ -2030,6 +2045,10 @@ pl022_probe(struct amba_device *adev, co
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->chipselect[i] = platform_info->chipselects[i];
+
/*
* Supports mode 0-3, loopback, and active low CS. Transfers are
* always MS bit first on the original pl022.
--- linux-2.6.orig/include/linux/amba/pl022.h
+++ linux-2.6/include/linux/amba/pl022.h
@@ -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;
};

/**

2012-08-21 16:01:06

by Roland Stigge

[permalink] [raw]

Subject: [PATCH v5 1/2] spi/pl022: Add chip select handling via GPIO

2012-08-21 16:12:08

by Alexandre Pereira da Silva

[permalink] [raw]

Subject: Re: [PATCH v5 1/2] spi/pl022: Add chip select handling via GPIO

On Tue, Aug 21, 2012 at 1:00 PM, Roland Stigge <[email protected]> wrote:
> 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 <[email protected]>
>
> Signed-off-by: Roland Stigge <[email protected]>

Acked-By: Alexandre Pereira da Silva <[email protected]>

> ---
> Applies to v3.6-rc2
>
> Patch set changes since v4:
> * Rename DT property: "pl022,num-chipselects" -> "num-cs"
> * Removed reference to Linux code in DT binding documentation
> * Removed property "pl022,hierarchy" - only support SPI master for now
> * Documented DT property pl022,interface
> * Removed property "pl022,slave-tx-disable" - not relevant in master mode
> * Added kerneldoc for cur_cs and chipselect list
> * Reorganized struct pl022 (int *chipselect)
> * Introduced int *chipselects to struct pl022_ssp_controller
> * Let platform data override DT data
> * Split patches into CS handling vs. DT support
>
> Changes since v3:
> * Proper use of IS_ENABLED
>
> Changes since v2:
> * Use IS_ENABLED instead of #ifdef
> * Remove bogus const change
>
> Changes since v1:
> * return EPROBE_DEFFER if gpios are not initialized yet
>
> Thanks Thierry Reding, Rob Herring and Linus Walleij for reviewing!
>
> drivers/spi/spi-pl022.c | 47 +++++++++++++++++++++++++++++++--------------
> include/linux/amba/pl022.h | 2 +
> 2 files changed, 35 insertions(+), 14 deletions(-)
>
> --- linux-2.6.orig/drivers/spi/spi-pl022.c
> +++ linux-2.6/drivers/spi/spi-pl022.c
> @@ -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)
> + * @chipselect: 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 *chipselect;
> };
>
> /**
> @@ -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_handl
> /* 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
>
> /* 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(st
>
> /* 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 p
> 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 p
> /* 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(st
>
> /* Setup the SPI using the per chip configuration */
> pl022->cur_chip = spi_get_ctldata(msg->spi);
> + pl022->cur_cs = pl022->chipselect[msg->spi->chip_select];
>
> restore_state(pl022);
> flush(pl022);
> @@ -1840,8 +1852,9 @@ static int pl022_setup(struct spi_device
> 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->chipselect[spi->chip_select]))
> + dev_warn(&spi->dev,
> + "chip select function is NULL for this chip\n");
> } else
> chip->cs_control = chip_info->cs_control;
>
> @@ -1993,7 +2006,7 @@ pl022_probe(struct amba_device *adev, co
> 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, co
> }
>
> /* 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 +2030,7 @@ pl022_probe(struct amba_device *adev, co
> pl022->master_info = platform_info;
> pl022->adev = adev;
> pl022->vendor = id->data;
> + pl022->chipselect = (int *)&master[1];
>
> /*
> * Bus Number Which has been Assigned to this SSP controller
> @@ -2030,6 +2045,10 @@ pl022_probe(struct amba_device *adev, co
> 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->chipselect[i] = platform_info->chipselects[i];
> +
> /*
> * Supports mode 0-3, loopback, and active low CS. Transfers are
> * always MS bit first on the original pl022.
> --- linux-2.6.orig/include/linux/amba/pl022.h
> +++ linux-2.6/include/linux/amba/pl022.h
> @@ -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;
> };
>
> /**

2012-08-22 11:09:32

by Linus Walleij

[permalink] [raw]

Subject: Re: [PATCH v5 1/2] spi/pl022: Add chip select handling via GPIO

On Tue, Aug 21, 2012 at 6:00 PM, Roland Stigge <[email protected]> wrote:

> 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 <[email protected]>
>
> Signed-off-by: Roland Stigge <[email protected]>

(...)
> /*
> * 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)
> + * @chipselect: 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 *chipselect;

Since this is an array, it should be named "chipselects" (plural).

(...)
> @@ -1840,8 +1852,9 @@ static int pl022_setup(struct spi_device
> 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->chipselect[spi->chip_select]))
> + dev_warn(&spi->dev,
> + "chip select function is NULL for this chip\n");

This dev_warn() is wrong. Alter to a proper warning message.

> @@ -2016,6 +2030,7 @@ pl022_probe(struct amba_device *adev, co
> pl022->master_info = platform_info;
> pl022->adev = adev;
> pl022->vendor = id->data;
> + pl022->chipselect = (int *)&master[1];

That last thing looks pretty awkward, atleast a comment
explaining what is going on is necessary. I would have done
it like this:

/* Point chipselects to allocated memory beyond the main struct */
pl022->chipselects = (int *) pl022 + sizeof(struct pl022);

Maybe it's simpler to just devm_kzalloc() this array.

Thanks,
Linus Walleij