[PATCH v3 0/8] can: rcar_canfd: Add support for Renesas RZ/G3S

[PATCH v3 0/8] can: rcar_canfd: Add support for Renesas RZ/G3S

[Claudiu Beznea]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

Hi,

Series adds CAN support for the Renesas RZ/G3S SoC. Along with it a typo
fix patch was added on the CAN driver.

Thank you,
Claudiu

Changes in v3:
- addressed sashiko review comments

Changes in v2:
- collected tags
- addressed sashiko review comments

Claudiu Beznea (8):
  clk: r9a08g045-cpg: Add clocks and resets for CAN-FD
  dt-bindings: can: renesas,rcar-canfd: Document RZ/G3S SoC
  can: rcar_canfd: Fix typos in macro names
  can: rcar_canfd: Allow the CAN FD clock to be sourced from fck
  can: rcar_canfd: Do not set registers selecting the CAN mode
  can: rcar_canfd: Add support for Renesas RZ/G3S
  arm64: dts: renesas: r9a08g045: Add CAN-FD node
  arm64: dts: renesas: rzg3s-smarc: Enable CAN-FD

 .../bindings/net/can/renesas,rcar-canfd.yaml  | 20 +++++-
 arch/arm64/boot/dts/renesas/r9a08g045.dtsi    | 39 +++++++++++
 .../boot/dts/renesas/rzg3s-smarc-switches.h   | 12 ++++
 arch/arm64/boot/dts/renesas/rzg3s-smarc.dtsi  | 46 +++++++++++++
 drivers/clk/renesas/r9a08g045-cpg.c           |  9 +++
 drivers/net/can/rcar/rcar_canfd.c             | 65 +++++++++++++++----
 6 files changed, 178 insertions(+), 13 deletions(-)

-- 
2.43.0

[PATCH v3 1/8] clk: r9a08g045-cpg: Add clocks and resets for CAN-FD

[Claudiu Beznea]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

Renesas RZ/G3S SoC has a CAN-FD IP. Add clocks and resets for it.

Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v3:
- none

Changes in v2:
- used R9A08G045_CLK_P4 ID for P4 clock
- still collected the tags; Biju, Geert, please let me know if you consider
  otherwise

 drivers/clk/renesas/r9a08g045-cpg.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/clk/renesas/r9a08g045-cpg.c b/drivers/clk/renesas/r9a08g045-cpg.c
index 624fc5e6fb24..ea2a6a71aebd 100644
--- a/drivers/clk/renesas/r9a08g045-cpg.c
+++ b/drivers/clk/renesas/r9a08g045-cpg.c
@@ -77,6 +77,7 @@ enum clk_ids {
 	CLK_SEL_PLL4,
 	CLK_P1_DIV2,
 	CLK_P3_DIV2,
+	CLK_P4_DIV2,
 	CLK_SD0_DIV4,
 	CLK_SD1_DIV4,
 	CLK_SD2_DIV4,
@@ -172,6 +173,8 @@ static const struct cpg_core_clk r9a08g045_core_clks[] __initconst = {
 	DEF_G3S_DIV("P3", R9A08G045_CLK_P3, CLK_PLL3_DIV2_4, DIVPL3C, G3S_DIVPL3C_STS,
 		    dtable_1_32, 0, 0, 0, NULL),
 	DEF_FIXED("P3_DIV2", CLK_P3_DIV2, R9A08G045_CLK_P3, 1, 2),
+	DEF_FIXED("P4", R9A08G045_CLK_P4, CLK_PLL2_DIV2, 1, 5),
+	DEF_FIXED("P4_DIV2", CLK_P4_DIV2, R9A08G045_CLK_P4, 1, 2),
 	DEF_FIXED("P5", R9A08G045_CLK_P5, CLK_PLL2_DIV2, 1, 4),
 	DEF_FIXED("ZT", R9A08G045_CLK_ZT, CLK_PLL3_DIV2_8, 1, 1),
 	DEF_FIXED("S0", R9A08G045_CLK_S0, CLK_SEL_PLL4, 1, 2),
@@ -274,6 +277,10 @@ static const struct rzg2l_mod_clk r9a08g045_mod_clks[] = {
 					MSTOP(BUS_MCPU2, BIT(5))),
 	DEF_MOD("scif5_clk_pck",	R9A08G045_SCIF5_CLK_PCK, R9A08G045_CLK_P0, 0x584, 5,
 					MSTOP(BUS_MCPU3, BIT(4))),
+	DEF_MOD("canfd_pclk",		R9A08G045_CANFD_PCLK, CLK_P4_DIV2, 0x594, 0,
+					MSTOP(BUS_MCPU2, BIT(9))),
+	DEF_MOD("canfd_clk_ram",	R9A08G045_CANFD_CLK_RAM, R9A08G045_CLK_P4, 0x594, 1,
+					MSTOP(BUS_MCPU2, BIT(9))),
 	DEF_MOD("gpio_hclk",		R9A08G045_GPIO_HCLK, R9A08G045_OSCCLK, 0x598, 0,
 					MSTOP(BUS_PERI_CPU, BIT(6))),
 	DEF_MOD("adc_adclk",		R9A08G045_ADC_ADCLK, R9A08G045_CLK_TSU, 0x5a8, 0,
@@ -324,6 +331,8 @@ static const struct rzg2l_reset r9a08g045_resets[] = {
 	DEF_RST(R9A08G045_SCIF3_RST_SYSTEM_N, 0x884, 3),
 	DEF_RST(R9A08G045_SCIF4_RST_SYSTEM_N, 0x884, 4),
 	DEF_RST(R9A08G045_SCIF5_RST_SYSTEM_N, 0x884, 5),
+	DEF_RST(R9A08G045_CANFD_RSTP_N, 0x894, 0),
+	DEF_RST(R9A08G045_CANFD_RSTC_N, 0x894, 1),
 	DEF_RST(R9A08G045_GPIO_RSTN, 0x898, 0),
 	DEF_RST(R9A08G045_GPIO_PORT_RESETN, 0x898, 1),
 	DEF_RST(R9A08G045_GPIO_SPARE_RESETN, 0x898, 2),
-- 
2.43.0

[PATCH v3 2/8] dt-bindings: can: renesas,rcar-canfd: Document RZ/G3S SoC

[Claudiu Beznea]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

The CAN FD controller found on the Renesas RZ/G3S SoC is largely compatible
with the variant present on the RZ/G3E SoC. The main differences are:
- the RZ/G3S provides only two CAN FD channels
- the RZ/G3S supports only CAN FD operation; the Channel n CAN FD
  Configuration Register does not implement the bits used to select
  classical CAN-only mode (bit 30) or CAN FD-only mode (bit 28);
  consequently, bit 31 (CAN FD Frame Distinction Enable) of the same
  register is also not implemented
- some bits in several registers (mainly reserved or status bits) are
  read-write on the RZ/G3S but read-only on the RZ/G3E; their behavior is
  otherwise identical: the bits read back as 0 on both SoCs and software
  is allowed to write only 0 to them on the RZ/G3S
- the RZ/G3S provides 256 acceptance filters, compared to 768 on the
  RZ/G3E
- the RZ/G3S can use PCLK clock as the CAN FD clock source through an
  internal clock divider, while also supporting an external CAN FD clock
  source

Since:
- the SoC clock generator provides to the CAN IP only the peripheral and
  the RAM clocks
- when sourced from the peripheral clock, the CAN-FD clock is obtained
  inside the IP itself by dividing the peripheral clock
- the assigned-clocks and assigned-clock-rates properties are specific to
  the CAN-FD clock
the assigned-clocks and assigned-clock-rates properties were dropped from
the required properties list of the Renesas RZ/G3S SoC.

Add documentation for the Renesas RZ/G3S SoC.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v3:
- updated the patch description to reflect RZ/G3S has 256 acceptance
  filters and RZ/G3E has 768 acceptance filters
- kept compatibles alphanumerically sorted

Changes in v2:
- forbid renesas,no-can-fd and renesas,fd-only since the IP supports
  only CAN-FD; for this didn't collect Biju's tag

 .../bindings/net/can/renesas,rcar-canfd.yaml  | 20 +++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml b/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml
index b9d9dd7a7967..bbaaef8f4282 100644
--- a/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml
+++ b/Documentation/devicetree/bindings/net/can/renesas,rcar-canfd.yaml
@@ -13,6 +13,7 @@ properties:
   compatible:
     oneOf:
       - enum:
+          - renesas,r9a08g045-canfd        # RZ/G3S
           - renesas,r9a09g047-canfd        # RZ/G3E
           - renesas,r9a09g077-canfd        # RZ/T2H
 
@@ -185,8 +186,6 @@ required:
   - clocks
   - clock-names
   - power-domains
-  - assigned-clocks
-  - assigned-clock-rates
   - channel0
   - channel1
 
@@ -198,6 +197,7 @@ allOf:
         compatible:
           contains:
             enum:
+              - renesas,r9a08g045-canfd
               - renesas,rzg2l-canfd
     then:
       properties:
@@ -266,6 +266,7 @@ allOf:
         compatible:
           contains:
             enum:
+              - renesas,r9a08g045-canfd
               - renesas,r9a09g077-canfd
               - renesas,rcar-gen3-canfd
               - renesas,rzg2l-canfd
@@ -330,6 +331,7 @@ allOf:
         compatible:
           contains:
             enum:
+              - renesas,r9a08g045-canfd
               - renesas,r9a09g047-canfd
               - renesas,rzg2l-canfd
     then:
@@ -350,6 +352,20 @@ allOf:
       properties:
         reset-names: false
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: renesas,r9a08g045-canfd
+    then:
+      properties:
+        renesas,no-can-fd: false
+        renesas,fd-only: false
+    else:
+      required:
+        - assigned-clocks
+        - assigned-clock-rates
+
 unevaluatedProperties: false
 
 examples:
-- 
2.43.0

[PATCH v3 3/8] can: rcar_canfd: Fix typos in macro names

[Claudiu Beznea]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

The bits 1..0 of the Channel n Control Register are named CHMDC (Channel
Mode select). Fix typos in macro names by replacing DMC with MDC.

Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v3:
- none

Changes in v2:
- collected tags

 drivers/net/can/rcar/rcar_canfd.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
index 4ee108abffb8..879f31c97276 100644
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -132,9 +132,9 @@
 #define RCANFD_CCTR_BEIE		BIT(8)
 #define RCANFD_CCTR_CSLPR		BIT(2)
 #define RCANFD_CCTR_CHMDC_MASK		(0x3)
-#define RCANFD_CCTR_CHDMC_COPM		(0x0)
-#define RCANFD_CCTR_CHDMC_CRESET	(0x1)
-#define RCANFD_CCTR_CHDMC_CHLT		(0x2)
+#define RCANFD_CCTR_CHMDC_COPM		(0x0)
+#define RCANFD_CCTR_CHMDC_CRESET	(0x1)
+#define RCANFD_CCTR_CHMDC_CHLT		(0x2)
 
 /* RSCFDnCFDCmSTS / RSCFDnCmSTS */
 #define RCANFD_CSTS_COMSTS		BIT(7)
@@ -828,7 +828,7 @@ static int rcar_canfd_reset_controller(struct rcar_canfd_global *gpriv)
 
 		rcar_canfd_update_bit(gpriv->base, RCANFD_CCTR(ch),
 				      RCANFD_CCTR_CHMDC_MASK,
-				      RCANFD_CCTR_CHDMC_CRESET);
+				      RCANFD_CCTR_CHMDC_CRESET);
 
 		/* Ensure Channel reset mode */
 		err = readl_poll_timeout((gpriv->base + RCANFD_CSTS(ch)), sts,
@@ -1504,7 +1504,7 @@ static int rcar_canfd_start(struct net_device *ndev)
 
 	/* Set channel to Operational mode */
 	rcar_canfd_update_bit(priv->base, RCANFD_CCTR(ch),
-			      RCANFD_CCTR_CHMDC_MASK, RCANFD_CCTR_CHDMC_COPM);
+			      RCANFD_CCTR_CHMDC_MASK, RCANFD_CCTR_CHMDC_COPM);
 
 	/* Verify channel mode change */
 	err = readl_poll_timeout((priv->base + RCANFD_CSTS(ch)), sts,
@@ -1578,7 +1578,7 @@ static void rcar_canfd_stop(struct net_device *ndev)
 
 	/* Transition to channel reset mode  */
 	rcar_canfd_update_bit(priv->base, RCANFD_CCTR(ch),
-			      RCANFD_CCTR_CHMDC_MASK, RCANFD_CCTR_CHDMC_CRESET);
+			      RCANFD_CCTR_CHMDC_MASK, RCANFD_CCTR_CHMDC_CRESET);
 
 	/* Check Channel reset mode */
 	err = readl_poll_timeout((priv->base + RCANFD_CSTS(ch)), sts,
-- 
2.43.0

[PATCH v3 4/8] can: rcar_canfd: Allow the CAN FD clock to be sourced from fck

[Claudiu Beznea]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

On the Renesas RZ/G3S, the CAN FD clock can be sourced either from fck
(the peripheral clock) or from an external clock (can_clk). When fck is
used, it is divided internally by the CAN FD controller.

Adjust the existing canfd clock handling code to support the RZ/G3S CAN.

The existing struct rcar_canfd_hw_info instances were updated to address
the request in the Link discussion.

Link: https://lore.kernel.org/all/1d9719e3-10ff-4cd8-b729-55fea93c37ce@wanadoo.fr
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v3:
- set gpriv->can_clk = NULL if info->fcan_pclk

Changes in v2:
- changed the logic to request canfd only if info->fcan_pclk and contrary
  get the fcan clock from pclk; for this didn't collect the Rb tag

 drivers/net/can/rcar/rcar_canfd.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
index 879f31c97276..7fa9cbbf8dde 100644
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -444,6 +444,7 @@ struct rcar_canfd_hw_info {
 	unsigned ch_interface_mode:1;	/* Has channel interface mode */
 	unsigned shared_can_regs:1;	/* Has shared classical can registers */
 	unsigned external_clk:1;	/* Has external clock */
+	unsigned fcan_pclk:1;		/* Has fcan sourced from pclk. */
 };
 
 /* Channel priv data */
@@ -617,6 +618,7 @@ static const struct rcar_canfd_hw_info rcar_gen3_hw_info = {
 	.ch_interface_mode = 0,
 	.shared_can_regs = 0,
 	.external_clk = 1,
+	.fcan_pclk = 0,
 };
 
 static const struct rcar_canfd_hw_info rcar_gen4_hw_info = {
@@ -634,6 +636,7 @@ static const struct rcar_canfd_hw_info rcar_gen4_hw_info = {
 	.ch_interface_mode = 1,
 	.shared_can_regs = 1,
 	.external_clk = 1,
+	.fcan_pclk = 0,
 };
 
 static const struct rcar_canfd_hw_info rzg2l_hw_info = {
@@ -651,6 +654,7 @@ static const struct rcar_canfd_hw_info rzg2l_hw_info = {
 	.ch_interface_mode = 0,
 	.shared_can_regs = 0,
 	.external_clk = 1,
+	.fcan_pclk = 0,
 };
 
 static const struct rcar_canfd_hw_info r9a09g047_hw_info = {
@@ -668,6 +672,7 @@ static const struct rcar_canfd_hw_info r9a09g047_hw_info = {
 	.ch_interface_mode = 1,
 	.shared_can_regs = 1,
 	.external_clk = 0,
+	.fcan_pclk = 0,
 };
 
 static const struct rcar_canfd_hw_info r9a09g077_hw_info = {
@@ -685,6 +690,7 @@ static const struct rcar_canfd_hw_info r9a09g077_hw_info = {
 	.ch_interface_mode = 1,
 	.shared_can_regs = 1,
 	.external_clk = 1,
+	.fcan_pclk = 0,
 };
 
 /* Helper functions */
@@ -2191,13 +2197,20 @@ static int rcar_canfd_probe(struct platform_device *pdev)
 	 */
 	gpriv->can_clk = devm_clk_get(dev, "can_clk");
 	if (IS_ERR(gpriv->can_clk) || (clk_get_rate(gpriv->can_clk) == 0)) {
-		gpriv->can_clk = devm_clk_get(dev, "canfd");
-		if (IS_ERR(gpriv->can_clk))
-			return dev_err_probe(dev, PTR_ERR(gpriv->can_clk),
-					     "cannot get canfd clock\n");
+		if (info->fcan_pclk) {
+			fcan_freq = clk_get_rate(gpriv->clkp);
+			gpriv->can_clk = NULL;
+		} else {
+			gpriv->can_clk = devm_clk_get(dev, "canfd");
+			if (IS_ERR(gpriv->can_clk))
+				return dev_err_probe(dev, PTR_ERR(gpriv->can_clk),
+						     "cannot get canfd clock\n");
+
+			fcan_freq = clk_get_rate(gpriv->can_clk);
+		}
 
 		/* CANFD clock may be further divided within the IP */
-		fcan_freq = clk_get_rate(gpriv->can_clk) / info->postdiv;
+		fcan_freq /= info->postdiv;
 	} else {
 		fcan_freq = clk_get_rate(gpriv->can_clk);
 		gpriv->extclk = gpriv->info->external_clk;
-- 
2.43.0

Re: [PATCH v3 4/8] can: rcar_canfd: Allow the CAN FD clock to be sourced from fck

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider:

Pre-existing issues:
- [High] The driver ignores `-EPROBE_DEFER` when acquiring the optional `can_clk`, leading to an incorrect clock source fallback or spurious probe failures.
- [High] Double free of `ndev` and UAF via `unregister_candev` if `register_candev` fails during channel probe.
- [High] Unbalanced clock disable and reset assert when `rcar_canfd_global_init` fails.
--

--- Patch [4]: [PATCH v3 4/8] can: rcar_canfd: Allow the CAN FD clock to be sourced from fck ---
commit a52a5e318c0ad2d299e214595e95da5df928f319
Author: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

can: rcar_canfd: Allow the CAN FD clock to be sourced from fck

This commit adjusts the clock handling in the RZ/G3S CAN FD driver to allow
the clock to be sourced from the peripheral clock instead of an external
clock. It also updates existing hardware info structures to support this.

Link: https://lore.kernel.org/all/1d9719e3-10ff-4cd8-b729-55fea93c37ce@wanadoo.fr

> diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
> index b40ae5998c1da..2e84dc5dfa34d 100644
> --- a/drivers/net/can/rcar/rcar_canfd.c
> +++ b/drivers/net/can/rcar/rcar_canfd.c
[ ... ]
> @@ -2190,13 +2196,20 @@ static int rcar_canfd_probe(struct platform_device *pdev)
>  	 */
>  	gpriv->can_clk = devm_clk_get(dev, "can_clk");
>  	if (IS_ERR(gpriv->can_clk) || (clk_get_rate(gpriv->can_clk) == 0)) {
> -		gpriv->can_clk = devm_clk_get(dev, "canfd");
> -		if (IS_ERR(gpriv->can_clk))
> -			return dev_err_probe(dev, PTR_ERR(gpriv->can_clk),
> -					     "cannot get canfd clock\n");
> +		if (info->fcan_pclk) {

[Severity: High]
This is a pre-existing issue, but the driver appears to ignore -EPROBE_DEFER
when acquiring the optional can_clk.

If can_clk is defined in the device tree but its provider has not yet probed,
devm_clk_get() returns -EPROBE_DEFER. Because the driver checks IS_ERR() and
blindly coalesces all errors into the fallback path, platforms with fcan_pclk
will silently fall back to the peripheral clock instead of deferring the probe.

Could this cause the CAN controller to run on the wrong clock, resulting in
invalid CAN baud rates? Should devm_clk_get_optional() be used here to
correctly propagate -EPROBE_DEFER?

> +			fcan_freq = clk_get_rate(gpriv->clkp);
> +			gpriv->can_clk = NULL;
> +		} else {
> +			gpriv->can_clk = devm_clk_get(dev, "canfd");
> +			if (IS_ERR(gpriv->can_clk))
> +				return dev_err_probe(dev, PTR_ERR(gpriv->can_clk),
> +						     "cannot get canfd clock\n");
> +
> +			fcan_freq = clk_get_rate(gpriv->can_clk);
> +		}

[Severity: High]
This isn't a bug introduced by this patch, but there appears to be a double free
and use-after-free risk during channel probe failure.

In rcar_canfd_channel_probe(), the channel pointer is assigned before calling
register_candev():

	gpriv->ch[priv->channel] = priv;
	err = register_candev(ndev);
	if (err) {
		...
		goto fail_candev;
	}

If register_candev() fails, the error path frees ndev (which embeds priv) via
free_candev(ndev), but leaves the dangling pointer in gpriv->ch.

When this error propagates back to rcar_canfd_probe(), the cleanup loop calls
rcar_canfd_channel_remove() for all channels:

	struct rcar_canfd_channel *priv = gpriv->ch[ch];
	if (priv) {
		unregister_candev(priv->ndev);
		netif_napi_del(&priv->napi);
		free_candev(priv->ndev);
	}

Will this dereference the dangling pointer, incorrectly call unregister_candev()
on invalid memory, and double-free ndev?

[Severity: High]
This is a pre-existing issue, but there seems to be an unbalanced clock disable
and reset assert when rcar_canfd_global_init() fails.

Inside rcar_canfd_global_init(), if an initialization step fails, the error
path correctly cleans up:

fail_ram_clk:
	clk_disable_unprepare(gpriv->clk_ram);
fail_clk:
	clk_disable_unprepare(gpriv->clkp);
fail_reset2:
	reset_control_assert(gpriv->rstc2);
fail_reset1:
	reset_control_assert(gpriv->rstc1);
	return err;

However, the error then propagates back to rcar_canfd_probe(), which jumps
to fail_mode and blindly calls rcar_canfd_global_deinit():

fail_mode:
	rcar_canfd_global_deinit(gpriv, false);

Since rcar_canfd_global_deinit() disables the exact same clocks and asserts
the exact same resets again, could this result in an unbalanced clock disable
(enable count underflow) and trigger kernel warnings?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260714173315.1981708-1-claudiu.beznea+renesas@tuxon.dev?part=4

[PATCH v3 5/8] can: rcar_canfd: Do not set registers selecting the CAN mode

[Claudiu Beznea]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

The bits 30 (classical CAN-only mode) and 28 (FD-only enable) of the
Channel n CAN-FD Configuration Register of the Renesas RZ/G3S SoC are not
available. The IP supports only CAN-FD mode. RZ/G3S HW manual (revision
1.30) specify the bits are read as zero and the write value should always
be zero.

Add the mode_select_na flag in struct rcar_canfd_hw_info to cover RZ/G3S
and avoid writing to unavailable bits.

The existing struct rcar_canfd_hw_info instances were updated to address
the request in the Link discussion.

Commit prepares for the addition of the Renesas RZ/G3S SoC.

Link: https://lore.kernel.org/all/1d9719e3-10ff-4cd8-b729-55fea93c37ce@wanadoo.fr
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v3:
- none

Changes in v2:
- collected the tags
- updated patch description to reflect this is a preparatory commit

 drivers/net/can/rcar/rcar_canfd.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
index 7fa9cbbf8dde..8ba8905c965a 100644
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -445,6 +445,7 @@ struct rcar_canfd_hw_info {
 	unsigned shared_can_regs:1;	/* Has shared classical can registers */
 	unsigned external_clk:1;	/* Has external clock */
 	unsigned fcan_pclk:1;		/* Has fcan sourced from pclk. */
+	unsigned mode_select_na:1;	/* Has no bits for selecting the mode. */
 };
 
 /* Channel priv data */
@@ -619,6 +620,7 @@ static const struct rcar_canfd_hw_info rcar_gen3_hw_info = {
 	.shared_can_regs = 0,
 	.external_clk = 1,
 	.fcan_pclk = 0,
+	.mode_select_na = 0,
 };
 
 static const struct rcar_canfd_hw_info rcar_gen4_hw_info = {
@@ -637,6 +639,7 @@ static const struct rcar_canfd_hw_info rcar_gen4_hw_info = {
 	.shared_can_regs = 1,
 	.external_clk = 1,
 	.fcan_pclk = 0,
+	.mode_select_na = 0,
 };
 
 static const struct rcar_canfd_hw_info rzg2l_hw_info = {
@@ -655,6 +658,7 @@ static const struct rcar_canfd_hw_info rzg2l_hw_info = {
 	.shared_can_regs = 0,
 	.external_clk = 1,
 	.fcan_pclk = 0,
+	.mode_select_na = 0,
 };
 
 static const struct rcar_canfd_hw_info r9a09g047_hw_info = {
@@ -673,6 +677,7 @@ static const struct rcar_canfd_hw_info r9a09g047_hw_info = {
 	.shared_can_regs = 1,
 	.external_clk = 0,
 	.fcan_pclk = 0,
+	.mode_select_na = 0,
 };
 
 static const struct rcar_canfd_hw_info r9a09g077_hw_info = {
@@ -691,6 +696,7 @@ static const struct rcar_canfd_hw_info r9a09g077_hw_info = {
 	.shared_can_regs = 1,
 	.external_clk = 1,
 	.fcan_pclk = 0,
+	.mode_select_na = 0,
 };
 
 /* Helper functions */
@@ -846,6 +852,9 @@ static int rcar_canfd_reset_controller(struct rcar_canfd_global *gpriv)
 		}
 
 		/* Set the controller into appropriate mode */
+		if (gpriv->info->mode_select_na)
+			continue;
+
 		if (gpriv->info->ch_interface_mode) {
 			/* Do not set CLOE and FDOE simultaneously */
 			if (!gpriv->fdmode) {
-- 
2.43.0

[PATCH v3 6/8] can: rcar_canfd: Add support for Renesas RZ/G3S

[Claudiu Beznea]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

Add support for Renesas RZ/G3S

The Renesas RZ/G3S CAN-FD controller is largely compatible with the
variant found on the Renesas RZ/G3E. The main differences are:
- the RZ/G3S provides 16 AFL pages
- the RZ/G3S supports only two channels
- the RZ/G3S supports only CAN-FD operation and does not implement the
  bits used to select between classical CAN-only and CAN FD-only modes.
- the RZ/G3S includes an internal divider that allows the peripheral
  clock to be used as the CAN FD clock source.

Add support for the Renesas RZ/G3S.

Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v3:
- updated max_aflpn as it refers to the number of available pages
  that could be used to access the acceptance filters; updated the
  patch description for this change

Changes in v2:
- initialized shared_global_irqs = 0 for RZ/G3S, to follow the request
  from https://lore.kernel.org/all/1d9719e3-10ff-4cd8-b729-55fea93c37ce@wanadoo.fr
- collected tags

 drivers/net/can/rcar/rcar_canfd.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
index 8ba8905c965a..d858778ff002 100644
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -661,6 +661,26 @@ static const struct rcar_canfd_hw_info rzg2l_hw_info = {
 	.mode_select_na = 0,
 };
 
+static const struct rcar_canfd_hw_info r9a08g045_hw_info = {
+	.nom_bittiming = &rcar_canfd_gen4_nom_bittiming_const,
+	.data_bittiming = &rcar_canfd_gen4_data_bittiming_const,
+	.tdc_const = &rcar_canfd_gen4_tdc_const,
+	.regs = &rcar_gen4_regs,
+	.sh = &rcar_gen4_shift_data,
+	.rnc_field_width = 16,
+	.max_aflpn = 15,
+	.max_cftml = 31,
+	.max_channels = 2,
+	.postdiv = 2,
+	.shared_global_irqs = 0,
+	.multi_channel_irqs = 1,
+	.ch_interface_mode = 1,
+	.shared_can_regs = 1,
+	.external_clk = 1,
+	.fcan_pclk = 1,
+	.mode_select_na = 1,
+};
+
 static const struct rcar_canfd_hw_info r9a09g047_hw_info = {
 	.nom_bittiming = &rcar_canfd_gen4_nom_bittiming_const,
 	.data_bittiming = &rcar_canfd_gen4_data_bittiming_const,
@@ -2384,6 +2404,7 @@ static DEFINE_SIMPLE_DEV_PM_OPS(rcar_canfd_pm_ops, rcar_canfd_suspend,
 
 static const __maybe_unused struct of_device_id rcar_canfd_of_table[] = {
 	{ .compatible = "renesas,r8a779a0-canfd", .data = &rcar_gen4_hw_info },
+	{ .compatible = "renesas,r9a08g045-canfd", .data = &r9a08g045_hw_info },
 	{ .compatible = "renesas,r9a09g047-canfd", .data = &r9a09g047_hw_info },
 	{ .compatible = "renesas,r9a09g077-canfd", .data = &r9a09g077_hw_info },
 	{ .compatible = "renesas,rcar-gen3-canfd", .data = &rcar_gen3_hw_info },
-- 
2.43.0

Re: [PATCH v3 6/8] can: rcar_canfd: Add support for Renesas RZ/G3S

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Allowing 'renesas,no-can-fd' on hardware that does not support classical CAN-only mode can cause RX FIFO corruption or unintended behavior.
--

--- Patch [6]: [PATCH v3 6/8] can: rcar_canfd: Add support for Renesas RZ/G3S ---
commit 72c4132759d04f40214ddc81cfa2c30db8c17906
Author: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

can: rcar_canfd: Add support for Renesas RZ/G3S

The Renesas RZ/G3S CAN-FD controller is largely compatible with the
variant found on the Renesas RZ/G3E. The RZ/G3S provides 16 AFL pages,
supports two channels, operates only in CAN-FD mode, and includes an
internal divider for the CAN FD clock source.

> diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
> index 5cb6048d610e9..2eabe4a8be8dc 100644
> --- a/drivers/net/can/rcar/rcar_canfd.c
> +++ b/drivers/net/can/rcar/rcar_canfd.c
> @@ -661,6 +661,26 @@ static const struct rcar_canfd_hw_info rzg2l_hw_info = {
>  	.mode_select_na = 0,
>  };
>  
> +static const struct rcar_canfd_hw_info r9a08g045_hw_info = {
> +	.nom_bittiming = &rcar_canfd_gen4_nom_bittiming_const,
> +	.data_bittiming = &rcar_canfd_gen4_data_bittiming_const,
> +	.tdc_const = &rcar_canfd_gen4_tdc_const,
> +	.regs = &rcar_gen4_regs,
> +	.sh = &rcar_gen4_shift_data,
> +	.rnc_field_width = 16,
> +	.max_aflpn = 15,
> +	.max_cftml = 31,
> +	.max_channels = 2,
> +	.postdiv = 2,
> +	.shared_global_irqs = 0,
> +	.multi_channel_irqs = 1,
> +	.ch_interface_mode = 1,
> +	.shared_can_regs = 1,
> +	.external_clk = 1,
> +	.fcan_pclk = 1,
> +	.mode_select_na = 1,

[Severity: High]
Since this hardware does not implement mode select bits and operates
exclusively in CAN-FD mode, could it cause internal hardware FIFO RAM overflow
if a device tree is ported over with the renesas,no-can-fd property?

In rcar_canfd_probe(), the renesas,no-can-fd property unconditionally forces
gpriv->fdmode = false.

If gpriv->fdmode is false:
1. rcar_canfd_configure_controller() will skip setting RCANFD_GCFG_CMPOC
   which normally truncates oversized payloads.
2. rcar_canfd_configure_rx() will incorrectly configure the RX FIFO payload size
   for 8 bytes (rfpls = 0).

Since the hardware is physically fixed in CAN-FD mode, would receiving a CAN-FD
frame larger than 8 bytes then write the full payload to the 8-byte FIFO slots
without truncation and corrupt memory?

> +};
> +

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260714173315.1981708-1-claudiu.beznea+renesas@tuxon.dev?part=6

[PATCH v3 7/8] arm64: dts: renesas: r9a08g045: Add CAN-FD node

[Claudiu Beznea]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

The Renesas RZ/G3S SoC includes a CAN-FD controller with two channels.
Add the corresponding device tree node.

Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v3:
- none

Changes in v2:
- collected tags

 arch/arm64/boot/dts/renesas/r9a08g045.dtsi | 39 ++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/arch/arm64/boot/dts/renesas/r9a08g045.dtsi b/arch/arm64/boot/dts/renesas/r9a08g045.dtsi
index 3a69bb246bab..fe46f3d9c7cc 100644
--- a/arch/arm64/boot/dts/renesas/r9a08g045.dtsi
+++ b/arch/arm64/boot/dts/renesas/r9a08g045.dtsi
@@ -29,6 +29,13 @@ audio_clk2: audio2-clk {
 		clock-frequency = <0>;
 	};
 
+	can_clk: can-clk {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		/* This value must be overridden by boards that provide it. */
+		clock-frequency = <0>;
+	};
+
 	cluster0_opp: opp-table-0 {
 		compatible = "operating-points-v2";
 		opp-shared;
@@ -498,6 +505,38 @@ ssi3: ssi@100a8c00 {
 			status = "disabled";
 		};
 
+		canfd: can@100c0000 {
+			compatible = "renesas,r9a08g045-canfd";
+			reg = <0 0x100c0000 0 0x20000>;
+			interrupts = <GIC_SPI 373 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 374 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 377 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 375 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 379 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 378 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 376 IRQ_TYPE_LEVEL_HIGH>,
+				     <GIC_SPI 380 IRQ_TYPE_LEVEL_HIGH>;
+			interrupt-names = "g_err", "g_recc",
+					  "ch0_err", "ch0_rec", "ch0_trx",
+					  "ch1_err", "ch1_rec", "ch1_trx";
+			clocks = <&cpg CPG_MOD R9A08G045_CANFD_PCLK>,
+				 <&cpg CPG_MOD R9A08G045_CANFD_CLK_RAM>,
+				 <&can_clk>;
+			clock-names = "fck", "ram_clk", "can_clk";
+			resets = <&cpg R9A08G045_CANFD_RSTP_N>,
+				 <&cpg R9A08G045_CANFD_RSTC_N>;
+			reset-names = "rstp_n", "rstc_n";
+			power-domains = <&cpg>;
+			status = "disabled";
+
+			channel0 {
+				status = "disabled";
+			};
+			channel1 {
+				status = "disabled";
+			};
+		};
+
 		cpg: clock-controller@11010000 {
 			compatible = "renesas,r9a08g045-cpg";
 			reg = <0 0x11010000 0 0x10000>;
-- 
2.43.0

[PATCH v3 8/8] arm64: dts: renesas: rzg3s-smarc: Enable CAN-FD

[Claudiu Beznea]

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

The two CAN FD channels available on the Renesas RZ/G3S SoC are routed
through the Renesas SMARC Carrier II board when used with the Renesas
RZ/G3S SMARC Module.

The CAN transceiver on the Carrier II board has its standby pins connected
to GPIOs that are selected through the SW_GPIO_CAN_PMOD switches. By
default, these switches route the GPIOs to the PMOD interfaces.

Enable the CAN FD controller and its two available channels.

Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

Changes in v3:
- none

Changes in v2:
- collected tags

 .../boot/dts/renesas/rzg3s-smarc-switches.h   | 12 +++++
 arch/arm64/boot/dts/renesas/rzg3s-smarc.dtsi  | 46 +++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/arch/arm64/boot/dts/renesas/rzg3s-smarc-switches.h b/arch/arm64/boot/dts/renesas/rzg3s-smarc-switches.h
index bbf908a5322c..198874ad9a65 100644
--- a/arch/arm64/boot/dts/renesas/rzg3s-smarc-switches.h
+++ b/arch/arm64/boot/dts/renesas/rzg3s-smarc-switches.h
@@ -37,4 +37,16 @@
  */
 #define SW_OPT_MUX4	SW_ON
 
+/*
+ * SW_GPIO_CAN_PMOD[x] switches' states:
+ * @SW_GPIO_CAN_PMOD1:
+ *	SW_OFF - GPIO8 connected to CAN0_STB (position 1-2)
+ *	SW_ON  - GPIO8 connected to PMOD1 (position 2-3)
+ * @SW_GPIO_CAN_PMOD2:
+ *	SW_OFF - GPIO9 connected to CAN1_STB (position 4-5)
+ *	SW_ON  - GPIO9 connected to PMOD1 (position 5-6)
+ */
+#define SW_GPIO_CAN_PMOD1	SW_ON
+#define SW_GPIO_CAN_PMOD2	SW_ON
+
 #endif /* __RZG3S_SMARC_SWITCHES_H__ */
diff --git a/arch/arm64/boot/dts/renesas/rzg3s-smarc.dtsi b/arch/arm64/boot/dts/renesas/rzg3s-smarc.dtsi
index 70af605168b0..2be684f55914 100644
--- a/arch/arm64/boot/dts/renesas/rzg3s-smarc.dtsi
+++ b/arch/arm64/boot/dts/renesas/rzg3s-smarc.dtsi
@@ -68,6 +68,24 @@ codec_dai: simple-audio-card,codec {
 		};
 	};
 
+	can_transceiver0: can-phy0 {
+		compatible = "ti,tcan1042";
+		#phy-cells = <0>;
+		max-bitrate = <8000000>;
+#if SW_GPIO_CAN_PMOD1 == SW_OFF
+		standby-gpios = <&pinctrl RZG2L_GPIO(13, 0) GPIO_ACTIVE_HIGH>;
+#endif
+	};
+
+	can_transceiver1: can-phy1 {
+		compatible = "ti,tcan1042";
+		#phy-cells = <0>;
+		max-bitrate = <8000000>;
+#if SW_GPIO_CAN_PMOD2 == SW_OFF
+		standby-gpios = <&pinctrl RZG2L_GPIO(13, 1) GPIO_ACTIVE_HIGH>;
+#endif
+	};
+
 	vcc_sdhi1: regulator-vcc-sdhi1 {
 		compatible = "regulator-fixed";
 		regulator-name = "SDHI1 Vcc";
@@ -92,6 +110,22 @@ &audio_clk2 {
 	clock-frequency = <12288000>;
 };
 
+&canfd {
+	pinctrl-0 = <&canfd_pins>;
+	pinctrl-names = "default";
+	status = "okay";
+
+	channel0 {
+		phys = <&can_transceiver0>;
+		status = "okay";
+	};
+
+	channel1 {
+		phys = <&can_transceiver1>;
+		status = "okay";
+	};
+};
+
 &ehci0 {
 	dr_mode = "otg";
 	status = "okay";
@@ -171,6 +205,18 @@ audio_clock_pins: audio-clock {
 		input-enable;
 	};
 
+	canfd_pins: canfd {
+		can0_pins: can0 {
+			pinmux = <RZG2L_PORT_PINMUX(6, 1, 3)>, /* CAN0_TX */
+				 <RZG2L_PORT_PINMUX(6, 2, 3)>; /* CAN0_RX */
+		};
+
+		can1_pins: can1 {
+			pinmux = <RZG2L_PORT_PINMUX(17, 0, 3)>, /* CAN1_TX */
+				 <RZG2L_PORT_PINMUX(17, 1, 3)>; /* CAN1_RX */
+		};
+	};
+
 	key-1-gpio-hog {
 		gpio-hog;
 		gpios = <RZG2L_GPIO(18, 0) GPIO_ACTIVE_LOW>;
-- 
2.43.0

Re: [PATCH v3 8/8] arm64: dts: renesas: rzg3s-smarc: Enable CAN-FD

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] CAN-FD channels are enabled unconditionally despite their transceivers being physically hardwired to standby mode by default.
--

--- Patch [8]: [PATCH v3 8/8] arm64: dts: renesas: rzg3s-smarc: Enable CAN-FD ---
commit 63f365e669fda8daca391467cd1aa1fe6a6efb02
Author: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

arm64: dts: renesas: rzg3s-smarc: Enable CAN-FD

This commit enables the two CAN FD channels available on the Renesas RZ/G3S
SoC, routing them through the SMARC Carrier II board. It adds nodes for the
transceivers and configures pinmuxing, noting that the standby pins share
GPIOs with PMOD interfaces via hardware switches.

> diff --git a/arch/arm64/boot/dts/renesas/rzg3s-smarc-switches.h b/arch/arm64/boot/dts/renesas/rzg3s-smarc-switches.h
> --- a/arch/arm64/boot/dts/renesas/rzg3s-smarc-switches.h
> +++ b/arch/arm64/boot/dts/renesas/rzg3s-smarc-switches.h

[ ... ]

> +/*
> + * SW_GPIO_CAN_PMOD[x] switches' states:
> + * @SW_GPIO_CAN_PMOD1:
> + *	SW_OFF - GPIO8 connected to CAN0_STB (position 1-2)
> + *	SW_ON  - GPIO8 connected to PMOD1 (position 2-3)
> + * @SW_GPIO_CAN_PMOD2:
> + *	SW_OFF - GPIO9 connected to CAN1_STB (position 4-5)
> + *	SW_ON  - GPIO9 connected to PMOD1 (position 5-6)
> + */
> +#define SW_GPIO_CAN_PMOD1	SW_ON
> +#define SW_GPIO_CAN_PMOD2	SW_ON
> +
>  #endif /* __RZG3S_SMARC_SWITCHES_H__ */

[ ... ]

> diff --git a/arch/arm64/boot/dts/renesas/rzg3s-smarc.dtsi b/arch/arm64/boot/dts/renesas/rzg3s-smarc.dtsi
> --- a/arch/arm64/boot/dts/renesas/rzg3s-smarc.dtsi
> +++ b/arch/arm64/boot/dts/renesas/rzg3s-smarc.dtsi

[ ... ]

> +	can_transceiver0: can-phy0 {
> +		compatible = "ti,tcan1042";
> +		#phy-cells = <0>;
> +		max-bitrate = <8000000>;
> +#if SW_GPIO_CAN_PMOD1 == SW_OFF
> +		standby-gpios = <&pinctrl RZG2L_GPIO(13, 0) GPIO_ACTIVE_HIGH>;
> +#endif
> +	};
> +
> +	can_transceiver1: can-phy1 {
> +		compatible = "ti,tcan1042";
> +		#phy-cells = <0>;
> +		max-bitrate = <8000000>;
> +#if SW_GPIO_CAN_PMOD2 == SW_OFF
> +		standby-gpios = <&pinctrl RZG2L_GPIO(13, 1) GPIO_ACTIVE_HIGH>;
> +#endif
> +	};

[ ... ]

> +&canfd {
> +	pinctrl-0 = <&canfd_pins>;
> +	pinctrl-names = "default";
> +	status = "okay";
> +
> +	channel0 {
> +		phys = <&can_transceiver0>;
> +		status = "okay";
> +	};
> +
> +	channel1 {
> +		phys = <&can_transceiver1>;
> +		status = "okay";
> +	};
> +};

[Severity: Medium]
Since SW_GPIO_CAN_PMOD1 and SW_GPIO_CAN_PMOD2 default to SW_ON, the
standby-gpios nodes are omitted for the transceivers.

Does unconditionally setting status = "okay" here expose broken CAN interfaces
to userspace by default? If the transceivers fall back to internal pull-ups and
enter standby mode, won't any transmission attempt blackhole and result in
immediate bus-off errors?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260714173315.1981708-1-claudiu.beznea+renesas@tuxon.dev?part=8