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Date: Tue, 5 Apr 2022 14:47:07 +0000
From: <Claudiu.Beznea@...rochip.com>
To: <p.zabel@...gutronix.de>, <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, Philipp,
On 05.04.2022 14:47, Philipp Zabel wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> 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.
I've double checked that. This would work if reset ids are continuous from
zero to rcdev.nr_resets. This the of_reset_simple_xlate:
static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
const struct of_phandle_args *reset_spec)
{
if (reset_spec->args[0] >= rcdev->nr_resets)
return -EINVAL;
return reset_spec->args[0];
}
But in this driver's case we have 3 ids: 4, 5, 6. That is the reason I had
this simple xlate function.
Thank you,
Claudiu Beznea
>
>> +
>> +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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