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Message-ID: <0ff9a7cd2e6261a0de32db3bf16901e3737efef8.camel@pengutronix.de>
Date: Tue, 05 Apr 2022 13:47:55 +0200
From: Philipp Zabel <p.zabel@...gutronix.de>
To: Claudiu Beznea <claudiu.beznea@...rochip.com>, robh+dt@...nel.org,
nicolas.ferre@...rochip.com, alexandre.belloni@...tlin.com,
sre@...nel.org
Cc: linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 6/8] power: reset: at91-reset: add reset_controller_dev
support
Hi Claudiu,
On Di, 2022-04-05 at 14:27 +0300, Claudiu Beznea wrote:
> SAMA7G5 reset controller has 5 extra lines that goes to different
> devices
> (3 lines to USB PHYs, 1 line to DDR controller, one line DDR PHY
> controller). These reset lines could be requested by different
> controller
> drivers (e.g. USB PHY driver) and these controllers' drivers could
> assert/deassert these lines when necessary. Thus add support for
> reset_controller_dev which brings this functionality.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
> ---
> drivers/power/reset/at91-reset.c | 92
> ++++++++++++++++++++++++++++++--
> 1 file changed, 88 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/power/reset/at91-reset.c
> b/drivers/power/reset/at91-reset.c
> index 0d721e27f545..b04df54c15d2 100644
> --- a/drivers/power/reset/at91-reset.c
> +++ b/drivers/power/reset/at91-reset.c
> @@ -17,6 +17,7 @@
> #include <linux/of_address.h>
> #include <linux/platform_device.h>
> #include <linux/reboot.h>
> +#include <linux/reset-controller.h>
>
> #include <soc/at91/at91sam9_ddrsdr.h>
> #include <soc/at91/at91sam9_sdramc.h>
> @@ -53,12 +54,16 @@ enum reset_type {
> struct at91_reset {
> void __iomem *rstc_base;
> void __iomem *ramc_base[2];
> + void __iomem *dev_base;
> + struct reset_controller_dev rcdev;
> struct clk *sclk;
> struct notifier_block nb;
> u32 args;
> u32 ramc_lpr;
> };
>
> +#define to_at91_reset(r) container_of(r, struct at91_reset, rcdev)
> +
> struct at91_reset_data {
> u32 reset_args;
> u32 n_device_reset;
> @@ -191,6 +196,79 @@ static const struct of_device_id
> at91_reset_of_match[] = {
> };
> MODULE_DEVICE_TABLE(of, at91_reset_of_match);
>
> +static int at91_reset_update(struct reset_controller_dev *rcdev,
> + unsigned long id, bool assert)
> +{
> + struct at91_reset *reset = to_at91_reset(rcdev);
> + u32 val;
> +
> + val = readl_relaxed(reset->dev_base);
> + if (assert)
> + val |= BIT(id);
> + else
> + val &= ~BIT(id);
> + writel_relaxed(val, reset->dev_base);
This read-modify-update should be protected by a spinlock.
> +
> + return 0;
> +}
> +
> +static int at91_reset_assert(struct reset_controller_dev *rcdev,
> + unsigned long id)
> +{
> + return at91_reset_update(rcdev, id, true);
> +}
> +
> +static int at91_reset_deassert(struct reset_controller_dev *rcdev,
> + unsigned long id)
> +{
> + return at91_reset_update(rcdev, id, false);
> +}
> +
> +static int at91_reset_dev_status(struct reset_controller_dev *rcdev,
> + unsigned long id)
> +{
> + struct at91_reset *reset = to_at91_reset(rcdev);
> + u32 val;
> +
> + val = readl_relaxed(reset->dev_base);
> +
> + return !!(val & BIT(id));
> +}
> +
> +static const struct reset_control_ops at91_reset_ops = {
> + .assert = at91_reset_assert,
> + .deassert = at91_reset_deassert,
> + .status = at91_reset_dev_status,
> +};
> +
> +static int at91_reset_of_xlate(struct reset_controller_dev *rcdev,
> + const struct of_phandle_args *reset_spec)
> +{
> + return reset_spec->args[0];
> +}
For 1:1 mappings there is no need for a custom of_xlate handler. Just
leave of_xlate and of_reset_n_cells empty.
> +
> +static int at91_rcdev_init(struct at91_reset *reset,
> + const struct at91_reset_data *data,
> + struct platform_device *pdev)
> +{
> + if (!data->n_device_reset)
> + return 0;
> +
> + reset->dev_base = devm_of_iomap(&pdev->dev, pdev->dev.of_node, 1,
> + NULL);
> + if (IS_ERR(reset->rstc_base))
Should check reset->dev_base here.
> + return -ENODEV;
> +
> + reset->rcdev.ops = &at91_reset_ops;
> + reset->rcdev.owner = THIS_MODULE;
> + reset->rcdev.of_node = pdev->dev.of_node;
> + reset->rcdev.nr_resets = data->n_device_reset;
> + reset->rcdev.of_reset_n_cells = 1;
> + reset->rcdev.of_xlate = at91_reset_of_xlate;
> +
> + return devm_reset_controller_register(&pdev->dev, &reset->rcdev);
> +}
> +
> static int __init at91_reset_probe(struct platform_device *pdev)
> {
> const struct of_device_id *match;
> @@ -244,6 +322,10 @@ static int __init at91_reset_probe(struct
> platform_device *pdev)
>
> platform_set_drvdata(pdev, reset);
>
> + ret = at91_rcdev_init(reset, data, pdev);
> + if (ret)
> + goto disable_clk;
> +
> if (of_device_is_compatible(pdev->dev.of_node,
> "microchip,sam9x60-rstc")) {
> u32 val = readl(reset->rstc_base + AT91_RSTC_MR);
>
> @@ -252,14 +334,16 @@ static int __init at91_reset_probe(struct
> platform_device *pdev)
> }
>
> ret = register_restart_handler(&reset->nb);
> - if (ret) {
> - clk_disable_unprepare(reset->sclk);
> - return ret;
> - }
> + if (ret)
> + goto disable_clk;
>
> at91_reset_status(pdev, reset->rstc_base);
>
> return 0;
> +
> +disable_clk:
> + clk_disable_unprepare(reset->sclk);
> + return ret;
> }
>
> static int __exit at91_reset_remove(struct platform_device *pdev)
regards
Philipp
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