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>

1 files changed, 34 insertions, 14 deletions

diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c
index 47c6753fb31b..cf47802f00c9 100644
--- 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.