Re: [PATCH v2 1/2] can: rcar_canfd: Add Classical CAN only mode support

[Rob Herring]

On Wed, Jun 22, 2016 at 01:31:46PM +0100, Ramesh Shanmugasundaram wrote:
> The controller can operate in one of the two global modes
>  - CAN FD only mode (default)
>  - Classical CAN (CAN2.0) only mode
> 
> This patch adds support for Classical CAN only mode. It can be enabled
> by defining the optional device tree property "renesas,no-can-fd" of this
> node.
> 
> Note: R-Car Gen3 h/w manual v0.51E shows bit6 of RSCFDnCFDGCFG as
> reserved, which is incorrect. This bit is same as RSCFDnGCFG.
> 
> Signed-off-by: Ramesh Shanmugasundaram 
> 
> ---
>  .../devicetree/bindings/net/can/rcar_canfd.txt |  21 +-

Acked-by: Rob Herring 

>  drivers/net/can/rcar/rcar_canfd.c  | 355 
> ++---
>  2 files changed, 255 insertions(+), 121 deletions(-)

[PATCH v2 1/2] can: rcar_canfd: Add Classical CAN only mode support

[Ramesh Shanmugasundaram]

The controller can operate in one of the two global modes
 - CAN FD only mode (default)
 - Classical CAN (CAN2.0) only mode

This patch adds support for Classical CAN only mode. It can be enabled
by defining the optional device tree property "renesas,no-can-fd" of this
node.

Note: R-Car Gen3 h/w manual v0.51E shows bit6 of RSCFDnCFDGCFG as
reserved, which is incorrect. This bit is same as RSCFDnGCFG.

Signed-off-by: Ramesh Shanmugasundaram 
---
 .../devicetree/bindings/net/can/rcar_canfd.txt |  21 +-
 drivers/net/can/rcar/rcar_canfd.c  | 355 ++---
 2 files changed, 255 insertions(+), 121 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/can/rcar_canfd.txt 
b/Documentation/devicetree/bindings/net/can/rcar_canfd.txt
index d45182b..22a6f10 100644
--- a/Documentation/devicetree/bindings/net/can/rcar_canfd.txt
+++ b/Documentation/devicetree/bindings/net/can/rcar_canfd.txt
@@ -32,6 +32,12 @@ below properties.
 - assigned-clocks: phandle of canfd clock.
 - assigned-clock-rates: maximum frequency of this clock.
 
+Optional property:
+The controller can operate in either CAN FD only mode (default) or
+Classical CAN only mode. The mode is global to both the channels. In order to
+enable the later, define the following optional property.
+ - renesas,no-can-fd: puts the controller in Classical CAN only mode.
+
 Example
 ---
 
@@ -63,12 +69,13 @@ SoC common .dtsi file:
 
 Board specific .dts file:
 
-E.g. below enables Channel 1 alone in the board.
+E.g. below enables Channel 1 alone in the board in Classical CAN only mode.
 
  {
-pinctrl-0 = <_pins>;
-pinctrl-names = "default";
-status = "okay";
+   pinctrl-0 = <_pins>;
+   pinctrl-names = "default";
+   renesas,no-can-fd;
+   status = "okay";
 
channel1 {
status = "okay";
@@ -79,9 +86,9 @@ E.g. below enables Channel 0 alone in the board using 
External clock
 as fCAN clock.
 
  {
-pinctrl-0 = <_pins _clk_pins>;
-pinctrl-names = "default";
-status = "okay";
+   pinctrl-0 = <_pins _clk_pins>;
+   pinctrl-names = "default";
+   status = "okay";
 
channel0 {
status = "okay";
diff --git a/drivers/net/can/rcar/rcar_canfd.c 
b/drivers/net/can/rcar/rcar_canfd.c
index a39d922..6bcc474 100644
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -16,8 +16,9 @@
  * mode, the controller acts as a CAN FD node that can also interoperate with
  * CAN 2.0 nodes.
  *
- * As of now, this driver does not support the Classical CAN (CAN 2.0) mode,
- * which is handled by a different register map compared to CAN FD only mode.
+ * To switch the controller to Classical CAN (CAN 2.0) only mode, add
+ * "renesas,no-can-fd" optional property to the device tree node. A h/w reset 
is
+ * also required to switch modes.
  *
  * Note: The h/w manual register naming convention is clumsy and not acceptable
  * to use as it is in the driver. However, those names are added as comments
@@ -48,15 +49,16 @@
 /* RSCFDnCFDGRMCFG */
 #define RCANFD_GRMCFG_RCMC BIT(0)
 
-/* RSCFDnCFDGCFG */
-#define RCANFD_GCFG_CMPOC  BIT(5)
+/* RSCFDnCFDGCFG / RSCFDnGCFG */
+#define RCANFD_GCFG_EEFE   BIT(6)
+#define RCANFD_GCFG_CMPOC  BIT(5)  /* CAN FD only */
 #define RCANFD_GCFG_DCSBIT(4)
 #define RCANFD_GCFG_DCEBIT(1)
 #define RCANFD_GCFG_TPRI   BIT(0)
 
-/* RSCFDnCFDGCTR */
+/* RSCFDnCFDGCTR / RSCFDnGCTR */
 #define RCANFD_GCTR_TSRST  BIT(16)
-#define RCANFD_GCTR_CFMPOFIE   BIT(11)
+#define RCANFD_GCTR_CFMPOFIE   BIT(11) /* CAN FD only */
 #define RCANFD_GCTR_THLEIE BIT(10)
 #define RCANFD_GCTR_MEIE   BIT(9)
 #define RCANFD_GCTR_DEIE   BIT(8)
@@ -66,7 +68,7 @@
 #define RCANFD_GCTR_GMDC_GRESET(0x1)
 #define RCANFD_GCTR_GMDC_GTEST (0x2)
 
-/* RSCFDnCFDGSTS */
+/* RSCFDnCFDGSTS / RSCFDnGSTS */
 #define RCANFD_GSTS_GRAMINIT   BIT(3)
 #define RCANFD_GSTS_GSLPSTSBIT(2)
 #define RCANFD_GSTS_GHLTSTSBIT(1)
@@ -74,44 +76,50 @@
 /* Non-operational status */
 #define RCANFD_GSTS_GNOPM  (BIT(0) | BIT(1) | BIT(2) | BIT(3))
 
-/* RSCFDnCFDGERFL */
+/* RSCFDnCFDGERFL / RSCFDnGERFL */
 #define RCANFD_GERFL_EEF1  BIT(17)
 #define RCANFD_GERFL_EEF0  BIT(16)
-#define RCANFD_GERFL_CMPOF BIT(3)
+#define RCANFD_GERFL_CMPOF BIT(3)  /* CAN FD only */
 #define RCANFD_GERFL_THLES BIT(2)
 #define RCANFD_GERFL_MES   BIT(1)
 #define RCANFD_GERFL_DEF   BIT(0)
 
-#define RCANFD_GERFL_ERR(x)((x) & (RCANFD_GERFL_EEF1 |\
-   RCANFD_GERFL_EEF0 |\
-   RCANFD_GERFL_MES |\
-