Re: [PATCH 1/2 v2] spi: s3c64xx: use "cs-gpios" from spi node instead of "cs-gpio"

Hello Sylwester,

Thanks for the review.
On 10 June 2014 16:09, Sylwester Nawrocki [off-list ref] wrote:

On 10/06/14 12:08, Naveen Krishna Chatradhi wrote:

quoted

Currently, spi-s3c64xx.c needs "cs-gpio" chip select GPIO to be
defined under "controller-data" node under each slave node.

&spi_x {
      cs-gpios <>;
      ...
      slave_node {

              controller-data {
                      cs-gpio = <>;
                      ...
              };
              ...
      };
      ...
};

Where as, SPI core and many other drivers uses "cs-gpios" for
from device tree node.

Hence, make changes in spi-s3c64xx.c driver to make use of
"cs-gpios" from SPI node(parent) instead of "cs-gpio" defined in
slaves "controller-data"(child) node.

Also updates the Device tree Documentation.

Signed-off-by: Naveen Krishna Chatradhi <redacted>
Cc: Javier Martinez Canillas <redacted>
Cc: Doug Anderson <dianders@chromium.org>
---
Changes since v1:
1. fixed a compilation warning thus squashing the other patch into this.
2. Updated device tree description in spi-samsung.txt

 .../devicetree/bindings/spi/spi-samsung.txt        |    8 ++-
 drivers/spi/spi-s3c64xx.c                          |   56 ++++++++++++--------
 2 files changed, 38 insertions(+), 26 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/spi-samsung.txt b/Documentation/devicetree/bindings/spi/spi-samsung.txt
index 86aa061..13bfcb5 100644
--- a/Documentation/devicetree/bindings/spi/spi-samsung.txt
+++ b/Documentation/devicetree/bindings/spi/spi-samsung.txt

@@ -42,15 +42,13 @@ Optional Board Specific Properties:
 - num-cs: Specifies the number of chip select lines supported. If
   not specified, the default number of chip select lines is set to 1.

+- cs-gpios: should specify GPIOs used for chipselects (see spi-bus.txt)
+
 SPI Controller specific data in SPI slave nodes:

 - The spi slave nodes should provide the following information which is required
   by the spi controller.

-  - cs-gpio: A gpio specifier that specifies the gpio line used as
-    the slave select line by the spi controller. The format of the gpio
-    specifier depends on the gpio controller.
-
   - samsung,spi-feedback-delay: The sampling phase shift to be applied on the
     miso line (to account for any lag in the miso line). The following are the
     valid values.

@@ -85,6 +83,7 @@ Example:
              #size-cells = <0>;
              pinctrl-names = "default";
              pinctrl-0 = <&spi0_bus>;
+             cs-gpios = <&gpa2 5 1 0 3>;

While at it, please change the GPIO specifier format, this one is not
valid any more.

Sure,  i will club it with the other comments.

quoted

              w25q80bw@0 {
                      #address-cells = <1>;

@@ -94,7 +93,6 @@ Example:
                      spi-max-frequency = <10000>;

                      controller-data {
-                             cs-gpio = <&gpa2 5 1 0 3>;
                              samsung,spi-feedback-delay = <0>;
                      };

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 75a5696..4594dde 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c

@@ -750,47 +750,56 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master,
 }

 static struct s3c64xx_spi_csinfo *s3c64xx_get_slave_ctrldata(
-                             struct spi_device *spi)
+                             struct spi_device *spi,
+                             struct s3c64xx_spi_csinfo *cs)
 {
-     struct s3c64xx_spi_csinfo *cs;
-     struct device_node *slave_np, *data_np = NULL;
-     struct s3c64xx_spi_driver_data *sdd;
+     struct device_node *data_np = NULL;
      u32 fb_delay = 0;

-     sdd = spi_master_get_devdata(spi->master);
-     slave_np = spi->dev.of_node;
-     if (!slave_np) {
-             dev_err(&spi->dev, "device node not found\n");
+     data_np = of_get_child_by_name(spi->dev.of_node, "controller-data");
+     if (!data_np) {
+             dev_err(&spi->dev, "child node 'controller-data' not found\n");
              return ERR_PTR(-EINVAL);
      }

-     data_np = of_get_child_by_name(slave_np, "controller-data");
-     if (!data_np) {
-             dev_err(&spi->dev, "child node 'controller-data' not found\n");
+     of_property_read_u32(data_np, "samsung,spi-feedback-delay", &fb_delay);
+     cs->fb_delay = fb_delay;
+     of_node_put(data_np);
+
+     return cs;
+}
+
+static struct s3c64xx_spi_csinfo *s3c64xx_get_cs_gpios(struct spi_device *spi)
+{
+     struct device_node *parent_np = NULL;
+     struct s3c64xx_spi_driver_data *sdd;
+     struct s3c64xx_spi_csinfo *cs;
+
+     parent_np = of_get_parent(spi->dev.of_node);
+     if (!parent_np) {
+             dev_err(&spi->dev, "Parent node not found\n");
              return ERR_PTR(-EINVAL);
      }

+     sdd = spi_master_get_devdata(spi->master);
+
      cs = kzalloc(sizeof(*cs), GFP_KERNEL);
      if (!cs) {
-             of_node_put(data_np);
+             of_node_put(parent_np);
              return ERR_PTR(-ENOMEM);
      }

      /* The CS line is asserted/deasserted by the gpio pin */
      if (sdd->cs_gpio)
-             cs->line = of_get_named_gpio(data_np, "cs-gpio", 0);
+             cs->line = of_get_named_gpio(parent_np, "cs-gpios", 0);

Can we support both "cs-gpio" and "cs-gpios" for backward compatibility ?
After your change all DTBs using the original pattern will not work with
new kernels any more. At least I would expect such backward compatibility
maintained for few kernel releases.

The reason behind removing the "cs-gpio" or not providing backward
compatibility was

1. Since spi-core started using "cs-gpios" string from spi device node
several months ago.
  The spi-s3c64xx.c driver is partially broken for more than 6 months.

2. Supporting "cs-gpio" would add extra bit of code.

I've corrected the dts files that were using "cs-gpio" under
"controller-data"(child node)
to use "cs-gpio" from spi device node (parent node).

I will make another version if you insist.

quoted

      if (!gpio_is_valid(cs->line)) {
              dev_err(&spi->dev, "chip select gpio is not specified or invalid\n");
-             kfree(cs);
-             of_node_put(data_np);
+             of_node_put(parent_np);
              return ERR_PTR(-EINVAL);
      }

-     of_property_read_u32(data_np, "samsung,spi-feedback-delay", &fb_delay);
-     cs->fb_delay = fb_delay;
-     of_node_put(data_np);
-     return cs;
+     return s3c64xx_get_slave_ctrldata(spi, cs);
 }

 /*

@@ -806,9 +815,14 @@ static int s3c64xx_spi_setup(struct spi_device *spi)
      struct s3c64xx_spi_info *sci;
      int err;

+     if (!spi->dev.of_node) {
+             dev_err(&spi->dev, "device node not found\n");
+             return -EINVAL;
+     }
+
      sdd = spi_master_get_devdata(spi->master);
      if (!cs && spi->dev.of_node) {
-             cs = s3c64xx_get_slave_ctrldata(spi);
+             cs = s3c64xx_get_cs_gpios(spi);
              spi->controller_data = cs;
      }

@@ -1077,7 +1091,7 @@ static int s3c64xx_spi_probe(struct platform_device *pdev)
      sdd->sfr_start = mem_res->start;
      sdd->cs_gpio = true;
      if (pdev->dev.of_node) {
-             if (!of_find_property(pdev->dev.of_node, "cs-gpio", NULL))
+             if (!of_find_property(pdev->dev.of_node, "cs-gpios", NULL))
                      sdd->cs_gpio = false;

Ditto.

I can do that, once we are finalized on having backward compatibility.

quoted

              ret = of_alias_get_id(pdev->dev.of_node, "spi");

--
Thanks!
Sylwester

-- 
Shine bright,
(: Nav :)