Re: [PATCH v2 2/3] can: sun4i_can: add support for R40 CAN controller

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11.01.2022 19:24, Andre Przywara пишет:
On Tue, 11 Jan 2022 18:57:08 +0300
Evgeny Boger <boger@xxxxxxxxxxxxxx> wrote:

Hi,

Allwinner R40 (also known as A40i, T3, V40) has a CAN controller. The
controller is the same as in earlier A10 and A20 SoCs, but needs reset
line to be deasserted before use.

This patch adds a new compatible for R40 CAN controller. Depending
on the compatible, reset line can be requested from DT.

Signed-off-by: Evgeny Boger <boger@xxxxxxxxxxxxxx>
---
  drivers/net/can/sun4i_can.c | 61 ++++++++++++++++++++++++++++++++++++-
  1 file changed, 60 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/sun4i_can.c b/drivers/net/can/sun4i_can.c
index 54aa7c25c4de..24a61326915e 100644
--- a/drivers/net/can/sun4i_can.c
+++ b/drivers/net/can/sun4i_can.c
@@ -61,6 +61,7 @@
  #include <linux/of.h>
  #include <linux/of_device.h>
  #include <linux/platform_device.h>
+#include <linux/reset.h>
#define DRV_NAME "sun4i_can" @@ -200,10 +201,20 @@
  #define SUN4I_CAN_MAX_IRQ	20
  #define SUN4I_MODE_MAX_RETRIES	100
+/**
+ * struct sun4ican_quirks - Differences between SoC variants.
+ *
+ * @has_reset: SoC needs reset deasserted.
+ */
+struct sun4ican_quirks {
+	bool		has_reset;
+};
+
  struct sun4ican_priv {
  	struct can_priv can;
  	void __iomem *base;
  	struct clk *clk;
+	struct reset_control *reset;
  	spinlock_t cmdreg_lock;	/* lock for concurrent cmd register writes */
  };
@@ -702,6 +713,13 @@ static int sun4ican_open(struct net_device *dev)
  		goto exit_irq;
  	}
+ /* software reset deassert */
+	err = reset_control_deassert(priv->reset);
+	if (err) {
+		netdev_err(dev, "could not deassert CAN reset\n");
+		goto exit_soft_reset;
+	}
+
  	/* turn on clocking for CAN peripheral block */
  	err = clk_prepare_enable(priv->clk);
  	if (err) {
@@ -723,6 +741,8 @@ static int sun4ican_open(struct net_device *dev)
  exit_can_start:
  	clk_disable_unprepare(priv->clk);
  exit_clock:
+	reset_control_assert(priv->reset);
+exit_soft_reset:
  	free_irq(dev->irq, dev);
  exit_irq:
  	close_candev(dev);
@@ -736,6 +756,7 @@ static int sun4ican_close(struct net_device *dev)
  	netif_stop_queue(dev);
  	sun4i_can_stop(dev);
  	clk_disable_unprepare(priv->clk);
+	reset_control_assert(priv->reset);
free_irq(dev->irq, dev);
  	close_candev(dev);
@@ -750,8 +771,27 @@ static const struct net_device_ops sun4ican_netdev_ops = {
  	.ndo_start_xmit = sun4ican_start_xmit,
  };
+static const struct sun4ican_quirks sun4ican_quirks_a10 = {
+	.has_reset = false,
+};
+
+static const struct sun4ican_quirks sun4ican_quirks_r40 = {
+	.has_reset = true,
+};
+
  static const struct of_device_id sun4ican_of_match[] = {
-	{.compatible = "allwinner,sun4i-a10-can"},
+	{
+		.compatible = "allwinner,sun4i-a10-can",
+		.data = &sun4ican_quirks_a10
+	},
+	{
+		.compatible = "allwinner,sun7i-a20-can",
+		.data = &sun4ican_quirks_a10
+	},
This one looks unnecessary, the binding says that it must be paired with
the A10 fallback.
We should only add an A20 compatible match if there is really a reason,
otherwise it encourages people to produce DTs with *only* the A20
compatible (violating the binding).

Right, thank you! Since this series has been around for a couple of months already,
and changes in v2 are trivial, would it make sense to submit v3 right away?


Cheers,
Andre

+	{
+		.compatible = "allwinner,sun8i-r40-can",
+		.data = &sun4ican_quirks_r40
+	},
  	{},
  };
@@ -771,10 +811,28 @@ static int sun4ican_probe(struct platform_device *pdev)
  {
  	struct device_node *np = pdev->dev.of_node;
  	struct clk *clk;
+	struct reset_control *reset = NULL;
  	void __iomem *addr;
  	int err, irq;
  	struct net_device *dev;
  	struct sun4ican_priv *priv;
+	const struct sun4ican_quirks *quirks;
+
+	quirks = of_device_get_match_data(&pdev->dev);
+	if (!quirks) {
+		dev_err(&pdev->dev, "failed to determine the quirks to use\n");
+		err = -ENODEV;
+		goto exit;
+	}
+
+	if (quirks->has_reset) {
+		reset = devm_reset_control_get_exclusive(&pdev->dev, NULL);
+		if (IS_ERR(reset)) {
+			dev_err(&pdev->dev, "unable to request reset\n");
+			err = PTR_ERR(reset);
+			goto exit;
+		}
+	}
clk = of_clk_get(np, 0);
  	if (IS_ERR(clk)) {
@@ -818,6 +876,7 @@ static int sun4ican_probe(struct platform_device *pdev)
  				       CAN_CTRLMODE_3_SAMPLES;
  	priv->base = addr;
  	priv->clk = clk;
+	priv->reset = reset;
  	spin_lock_init(&priv->cmdreg_lock);
platform_set_drvdata(pdev, dev);




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