Re: [PATCH v2 4/4] i3c: renesas: Add suspend/resume support

[Frank Li <Frank.li@nxp.com>]

On Tue, Dec 30, 2025 at 11:39:39AM +0100, Tommaso Merciai wrote:
> The Renesas I3C controller does not retain its register state across system
> suspend, requiring the driver to explicitly save and restore hardware
> configuration.
>
> Add suspend and resume NOIRQ callbacks to handle system sleep transitions.
>
> During suspend, save the Device Address Table (DAT) entries, assert reset
> lines, and disable all related clocks to allow the controller to enter a
> low-power state.
>
> On resume, re-enable clocks and reset lines in the proper order. Restore
> the REFCKCTL register, master dynamic address, and all DAT entries, then
> reinitialize the controller.
>
> Store the REFCLK divider value, and the master dynamic address to restore
> timing and addressing configuration after resume.
>
> Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
> ---
> v1->v2:
>  - Updated commit as v1 has been split into smaller patches.
>  - Use clock bulk API into renesas_i3c_suspend_noirq() and
>    renesas_i3c_resume_noirq().
>  - Updated commit body accordingly.
>
>  drivers/i3c/master/renesas-i3c.c | 85 ++++++++++++++++++++++++++++++++
>  1 file changed, 85 insertions(+)
>
> diff --git a/drivers/i3c/master/renesas-i3c.c b/drivers/i3c/master/renesas-i3c.c
> index 4f076c372b36..f089bbf19fa5 100644
> --- a/drivers/i3c/master/renesas-i3c.c
> +++ b/drivers/i3c/master/renesas-i3c.c
> @@ -254,16 +254,19 @@ struct renesas_i3c {
>  	enum i3c_internal_state internal_state;
>  	u16 maxdevs;
>  	u32 free_pos;
> +	u32 dyn_addr;
>  	u32 i2c_STDBR;
>  	u32 i3c_STDBR;
>  	unsigned long rate;
>  	u8 addrs[RENESAS_I3C_MAX_DEVS];
>  	struct renesas_i3c_xferqueue xferqueue;
>  	void __iomem *regs;
> +	u32 *DATBASn;
>  	struct clk_bulk_data clks[3];
>  	u8 num_clks;
>  	struct reset_control *presetn;
>  	struct reset_control *tresetn;
> +	u8 refclk_div;
>  };
>
>  struct renesas_i3c_i2c_dev_data {
> @@ -615,6 +618,7 @@ static int renesas_i3c_bus_init(struct i3c_master_controller *m)
>  					   EXTBR_EBRHP(pp_high_ticks));
>
>  	renesas_writel(i3c->regs, REFCKCTL, REFCKCTL_IREFCKS(cks));
> +	i3c->refclk_div = cks;
>
>  	/* I3C hw init*/
>  	renesas_i3c_hw_init(i3c);
> @@ -623,6 +627,7 @@ static int renesas_i3c_bus_init(struct i3c_master_controller *m)
>  	if (ret < 0)
>  		return ret;
>
> +	i3c->dyn_addr = ret;
>  	renesas_writel(i3c->regs, MSDVAD, MSDVAD_MDYAD(ret) | MSDVAD_MDYADV);
>
>  	memset(&info, 0, sizeof(info));
> @@ -1390,6 +1395,13 @@ static int renesas_i3c_probe(struct platform_device *pdev)
>  	i3c->maxdevs = RENESAS_I3C_MAX_DEVS;
>  	i3c->free_pos = GENMASK(i3c->maxdevs - 1, 0);
>
> +	/* Allocate dynamic Device Address Table backup. */
> +	i3c->DATBASn = devm_kzalloc(&pdev->dev,
> +				    sizeof(u32) * i3c->maxdevs,
> +				    GFP_KERNEL);

nit: can you move it to previous line to reduce line number

> +	if (!i3c->DATBASn)
> +		return -ENOMEM;
> +
>  	return i3c_master_register(&i3c->base, &pdev->dev, &renesas_i3c_ops, false);
>  }
>
> @@ -1400,6 +1412,78 @@ static void renesas_i3c_remove(struct platform_device *pdev)
>  	i3c_master_unregister(&i3c->base);
>  }
>
> +static int renesas_i3c_suspend_noirq(struct device *dev)
> +{
> +	struct renesas_i3c *i3c = dev_get_drvdata(dev);
> +	int i, ret;
> +
> +	i2c_mark_adapter_suspended(&i3c->base.i2c);
> +
> +	/* Store Device Address Table values. */
> +	for (i = 0; i < i3c->maxdevs; i++)
> +		i3c->DATBASn[i] = renesas_readl(i3c->regs, DATBAS(i));
> +
> +	ret = reset_control_assert(i3c->presetn);
> +	if (ret)
> +		return ret;
> +
> +	ret = reset_control_assert(i3c->tresetn);
> +	if (ret) {
> +		reset_control_deassert(i3c->presetn);
> +		return ret;
> +	}
> +
> +	clk_bulk_disable_unprepare(i3c->num_clks, i3c->clks);
> +
> +	return 0;
> +}
> +
> +static int renesas_i3c_resume_noirq(struct device *dev)
> +{
> +	struct renesas_i3c *i3c = dev_get_drvdata(dev);
> +	int i, ret;
> +
> +	ret = reset_control_deassert(i3c->presetn);
> +	if (ret)
> +		return ret;
> +
> +	ret = reset_control_deassert(i3c->tresetn);
> +	if (ret)
> +		goto err_presetn;
> +
> +	ret = clk_bulk_prepare_enable(i3c->num_clks, i3c->clks);
> +	if (ret)
> +		goto err_tresetn;
> +
> +	/* Re-store I3C registers value. */
> +	renesas_writel(i3c->regs, REFCKCTL,
> +		       REFCKCTL_IREFCKS(i3c->refclk_div));
> +	renesas_writel(i3c->regs, MSDVAD, MSDVAD_MDYADV |
> +		       MSDVAD_MDYAD(i3c->dyn_addr));
> +
> +	/* Restore Device Address Table values. */
> +	for (i = 0; i < i3c->maxdevs; i++)
> +		renesas_writel(i3c->regs, DATBAS(i), i3c->DATBASn[i]);
> +
> +	/* I3C hw init. */
> +	renesas_i3c_hw_init(i3c);
> +
> +	i2c_mark_adapter_resumed(&i3c->base.i2c);
> +
> +	return 0;
> +
> +err_tresetn:
> +	clk_bulk_disable_unprepare(i3c->num_clks, i3c->clks)

look like it should be
	reset_control_assert(i3c->tresetn);

Frank

> +err_presetn:
> +	reset_control_assert(i3c->presetn);
> +	return ret;
> +}
> +
> +static const struct dev_pm_ops renesas_i3c_pm_ops = {
> +	NOIRQ_SYSTEM_SLEEP_PM_OPS(renesas_i3c_suspend_noirq,
> +				  renesas_i3c_resume_noirq)
> +};
> +
>  static const struct renesas_i3c_config empty_i3c_config = {
>  };
>
> @@ -1420,6 +1504,7 @@ static struct platform_driver renesas_i3c = {
>  	.driver = {
>  		.name = "renesas-i3c",
>  		.of_match_table = renesas_i3c_of_ids,
> +		.pm = pm_sleep_ptr(&renesas_i3c_pm_ops),
>  	},
>  };
>  module_platform_driver(renesas_i3c);
> --
> 2.43.0
>