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: 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>

diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c
index 47c6753fb31b113591cd3f67472af85d7b6ce8c6..cf47802f00c982518e6cf4358e29783a8bb7ee3e 100644 (file)
--- a/drivers/spi/spi-pl022.c
+++ b/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)
+ * @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;
-               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;
 
@@ -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.

diff --git a/include/linux/amba/pl022.h b/include/linux/amba/pl022.h
index fe1d7b283cb633c4be48d465f5fa572333929fe8..854b7294f6c64f77b636c38188897a9621e7bbff 100644 (file)
--- a/include/linux/amba/pl022.h
+++ b/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;
 };
 
 /**