spi: bcm2835: reduce the abuse of the GPIO API

[linux-2.6-microblaze.git] / drivers / spi / spi-bcm2835.c

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index a457ad2..c9078fe 100644 (file)
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -11,6 +11,7 @@
  * spi-atmel.c, Copyright (C) 2006 Atmel Corporation
  */
 
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/debugfs.h>
@@ -26,9 +27,10 @@
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/gpio/consumer.h>
-#include <linux/gpio/machine.h> /* FIXME: using chip internals */
-#include <linux/gpio/driver.h> /* FIXME: using chip internals */
+#include <linux/gpio/machine.h> /* FIXME: using GPIO lookup tables */
 #include <linux/of_irq.h>
+#include <linux/overflow.h>
+#include <linux/slab.h>
 #include <linux/spi/spi.h>
 
 /* SPI register offsets */
@@ -83,6 +85,7 @@ MODULE_PARM_DESC(polling_limit_us,
  * struct bcm2835_spi - BCM2835 SPI controller
  * @regs: base address of register map
  * @clk: core clock, divided to calculate serial clock
+ * @cs_gpio: chip-select GPIO descriptor
  * @clk_hz: core clock cached speed
  * @irq: interrupt, signals TX FIFO empty or RX FIFO ¾ full
  * @tfr: SPI transfer currently processed
@@ -117,6 +120,7 @@ MODULE_PARM_DESC(polling_limit_us,
 struct bcm2835_spi {
        void __iomem *regs;
        struct clk *clk;
+       struct gpio_desc *cs_gpio;
        unsigned long clk_hz;
        int irq;
        struct spi_transfer *tfr;
@@ -1156,15 +1160,11 @@ static void bcm2835_spi_handle_err(struct spi_controller *ctlr,
        bcm2835_spi_reset_hw(bs);
 }
 
-static int chip_match_name(struct gpio_chip *chip, void *data)
-{
-       return !strcmp(chip->label, data);
-}
-
 static void bcm2835_spi_cleanup(struct spi_device *spi)
 {
        struct bcm2835_spidev *target = spi_get_ctldata(spi);
        struct spi_controller *ctlr = spi->controller;
+       struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
 
        if (target->clear_rx_desc)
                dmaengine_desc_free(target->clear_rx_desc);
@@ -1175,6 +1175,9 @@ static void bcm2835_spi_cleanup(struct spi_device *spi)
                                 sizeof(u32),
                                 DMA_TO_DEVICE);
 
+       gpiod_put(bs->cs_gpio);
+       spi_set_csgpiod(spi, 0, NULL);
+
        kfree(target);
 }
 
@@ -1221,7 +1224,7 @@ static int bcm2835_spi_setup(struct spi_device *spi)
        struct spi_controller *ctlr = spi->controller;
        struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
        struct bcm2835_spidev *target = spi_get_ctldata(spi);
-       struct gpio_chip *chip;
+       struct gpiod_lookup_table *lookup __free(kfree) = NULL;
        int ret;
        u32 cs;
 
@@ -1288,29 +1291,36 @@ static int bcm2835_spi_setup(struct spi_device *spi)
        }
 
        /*
-        * Translate native CS to GPIO
+        * TODO: The code below is a slightly better alternative to the utter
+        * abuse of the GPIO API that I found here before. It creates a
+        * temporary lookup table, assigns it to the SPI device, gets the GPIO
+        * descriptor and then releases the lookup table.
         *
-        * FIXME: poking around in the gpiolib internals like this is
-        * not very good practice. Find a way to locate the real problem
-        * and fix it. Why is the GPIO descriptor in spi->cs_gpiod
-        * sometimes not assigned correctly? Erroneous device trees?
+        * More on the problem that it addresses:
+        *   https://www.spinics.net/lists/linux-gpio/msg36218.html
         */
+       lookup = kzalloc(struct_size(lookup, table, 1), GFP_KERNEL);
+       if (!lookup) {
+               ret = -ENOMEM;
+               goto err_cleanup;
+       }
 
-       /* get the gpio chip for the base */
-       chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
-       if (!chip)
-               return 0;
+       lookup->dev_id = dev_name(&spi->dev);
+       lookup->table[0] = GPIO_LOOKUP("pinctrl-bcm2835",
+                                      8 - (spi_get_chipselect(spi, 0)),
+                                      "cs", GPIO_LOOKUP_FLAGS_DEFAULT);
 
-       spi_set_csgpiod(spi, 0, gpiochip_request_own_desc(chip,
-                                                         8 - (spi_get_chipselect(spi, 0)),
-                                                         DRV_NAME,
-                                                         GPIO_LOOKUP_FLAGS_DEFAULT,
-                                                         GPIOD_OUT_LOW));
-       if (IS_ERR(spi_get_csgpiod(spi, 0))) {
-               ret = PTR_ERR(spi_get_csgpiod(spi, 0));
+       gpiod_add_lookup_table(lookup);
+
+       bs->cs_gpio = gpiod_get(&spi->dev, "cs", GPIOD_OUT_LOW);
+       gpiod_remove_lookup_table(lookup);
+       if (IS_ERR(bs->cs_gpio)) {
+               ret = PTR_ERR(bs->cs_gpio);
                goto err_cleanup;
        }
 
+       spi_set_csgpiod(spi, 0, bs->cs_gpio);
+
        /* and set up the "mode" and level */
        dev_info(&spi->dev, "setting up native-CS%i to use GPIO\n",
                 spi_get_chipselect(spi, 0));