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).
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);
