Re: [PATCH v5 4/4] i3c: renesas: Add suspend/resume support

[Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>]

Hi Adrian,
Thanks for your comment.

On Fri, Jan 09, 2026 at 04:50:00PM +0200, Adrian Hunter wrote:
> On 07/01/2026 12:33, 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.
> > 
> > Reviewed-by: Frank Li <Frank.Li@nxp.com>
> > Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
> > ---
> > v4->v5:
> >  - Collected tag.
> > 
> > v3->v4:
> >  - Use clk_bulk_disable/enable() into renesas_i3c_suspend/resume_noirq()
> >    instead of clk_bulk_prepare_enable()/clk_bulk_disable_unprepare()
> > 
> > v2->v3:
> >  - Fixed error path into renesas_i3c_resume_noirq() and
> >    renesas_i3c_suspend_noirq() function.
> >  - Moved up one line sizeof(u32) * i3c->maxdevs into devm_kzalloc() call.
> > 
> > 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().
> > 
> >  drivers/i3c/master/renesas-i3c.c | 89 ++++++++++++++++++++++++++++++++
> >  1 file changed, 89 insertions(+)
> > 
> > diff --git a/drivers/i3c/master/renesas-i3c.c b/drivers/i3c/master/renesas-i3c.c
> > index 008b6ee60e26..528bccc2c68e 100644
> > --- a/drivers/i3c/master/renesas-i3c.c
> > +++ b/drivers/i3c/master/renesas-i3c.c
> > @@ -256,16 +256,19 @@ 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;
> >  	struct reset_control *presetn;
> >  	struct reset_control *tresetn;
> >  	u8 num_clks;
> > +	u8 refclk_div;
> >  };
> >  
> >  struct renesas_i3c_i2c_dev_data {
> > @@ -609,6 +612,7 @@ 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);
> > @@ -617,6 +621,7 @@ 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));
> > @@ -1363,6 +1368,12 @@ 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);
> > +	if (!i3c->DATBASn)
> > +		return -ENOMEM;
> > +
> >  	return i3c_master_register(&i3c->base, &pdev->dev, &renesas_i3c_ops, false);
> >  }
> >  
> > @@ -1373,6 +1384,83 @@ 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)
> > +		goto err_mark_resumed;
> > +
> > +	ret = reset_control_assert(i3c->tresetn);
> > +	if (ret)
> > +		goto err_presetn;
> > +
> > +	clk_bulk_disable(i3c->num_clks, i3c->clks);
> > +
> > +	return 0;
> > +
> > +err_presetn:
> > +	reset_control_deassert(i3c->presetn);
> > +err_mark_resumed:
> > +	i2c_mark_adapter_resumed(&i3c->base.i2c);
> > +
> > +	return ret;
> > +}
> > +
> > +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_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;
> 
> Is it assumed I3C target devices do not lose their dynamic addresses
> during suspend?

Testing with the following setup:
NXP P3T1085UK-ARD connected to the RZ/G3E SMARC SoM
via the RZ/G3E SMARC breakout board.

The dynamic address is not lost during the suspend/resume cycle.

Kind Regards,
Tommaso

> 
> > +
> > +err_tresetn:
> > +	reset_control_assert(i3c->tresetn);
> > +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 of_device_id renesas_i3c_of_ids[] = {
> >  	{ .compatible = "renesas,r9a08g045-i3c" },
> >  	{ .compatible = "renesas,r9a09g047-i3c" },
> > @@ -1386,6 +1474,7 @@ 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);
>