linux-kernel - Re: [PATCH v3 4/8] memory: Add STM32 Octo Memory Manager driver

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Message-ID: <a74c3202-7a64-483d-907e-9a562e9dcd03@wanadoo.fr>
Date: Tue, 11 Feb 2025 19:16:49 +0100
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: patrice.chotard@...s.st.com
Cc: alexandre.torgue@...s.st.com, arnd@...db.de, broonie@...nel.org,
 catalin.marinas@....com, christophe.kerello@...s.st.com,
 conor+dt@...nel.org, devicetree@...r.kernel.org, gregkh@...uxfoundation.org,
 krzk+dt@...nel.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-spi@...r.kernel.org,
 linux-stm32@...md-mailman.stormreply.com, mcoquelin.stm32@...il.com,
 p.zabel@...gutronix.de, robh@...nel.org, will@...nel.org
Subject: Re: [PATCH v3 4/8] memory: Add STM32 Octo Memory Manager driver

Le 10/02/2025 à 14:18, 
patrice.chotard-rj0Iel/JR4NBDgjK7y7TUQ@...lic.gmane.org a écrit :
> From: Patrice Chotard <patrice.chotard-rj0Iel/JR4NBDgjK7y7TUQ@...lic.gmane.org>
> 
> Octo Memory Manager driver (OMM) manages:
>    - the muxing between 2 OSPI busses and 2 output ports.
>      There are 4 possible muxing configurations:
>        - direct mode (no multiplexing): OSPI1 output is on port 1 and OSPI2
>          output is on port 2
>        - OSPI1 and OSPI2 are multiplexed over the same output port 1
>        - swapped mode (no multiplexing), OSPI1 output is on port 2,
>          OSPI2 output is on port 1
>        - OSPI1 and OSPI2 are multiplexed over the same output port 2
>    - the split of the memory area shared between the 2 OSPI instances.
>    - chip select selection override.
>    - the time between 2 transactions in multiplexed mode.
>    - check firewall access.

...

> diff --git a/drivers/memory/stm32_omm.c b/drivers/memory/stm32_omm.c
> new file mode 100644
> index 000000000000..af69137bfba2
> --- /dev/null
> +++ b/drivers/memory/stm32_omm.c
> @@ -0,0 +1,520 @@
> +// SPDX-License-Identifier: GPL

Not sure this SPDX-License-Identifier exists.

> +/*
> + * Copyright (C) STMicroelectronics 2024 - All Rights Reserved

...

> +	pm_runtime_enable(dev);
> +
> +	/* check if OMM's resource access is granted */
> +	ret = stm32_omm_check_access(dev, dev->of_node);
> +	if (ret < 0 && ret != -EACCES)
> +		goto err_clk_release;

Should we call, here and below, pm_runtime_disable() in the error 
handling path, as done in the remove function?

> +
> +	if (!ret && child_access_granted == OMM_CHILD_NB) {
> +		/* Ensure both OSPI instance are disabled before configuring OMM */
> +		ret = stm32_omm_disable_child(dev);
> +		if (ret)
> +			goto err_clk_release;
> +
> +		ret = stm32_omm_configure(dev);
> +		if (ret)
> +			goto err_clk_release;
> +	} else {
> +		dev_dbg(dev, "Octo Memory Manager resource's access not granted\n");
> +		/*
> +		 * AMCR can't be set, so check if current value is coherent
> +		 * with memory-map areas defined in DT
> +		 */
> +		ret = stm32_omm_set_amcr(dev, false);
> +		if (ret)
> +			goto err_clk_release;
> +	}
> +
> +	/* for each child, if resource access is granted and status "okay", probe it */
> +	for (i = 0; i < omm->nb_child; i++) {
> +		if (!child_access[i] || !of_device_is_available(omm->child[i].node))
> +			continue;
> +
> +		vdev = of_platform_device_create(omm->child[i].node, NULL, NULL);
> +		if (!vdev) {
> +			dev_err(dev, "Failed to create Octo Memory Manager child\n");
> +			for (j = i; j > 0; --j) {
> +				if (omm->child[j].dev)
> +					of_platform_device_destroy(omm->child[j].dev, NULL);
> +			}
> +
> +			ret = -EINVAL;
> +			goto err_clk_release;
> +		}
> +		omm->child[i].dev = &vdev->dev;
> +	}
> +
> +err_clk_release:
> +	for (i = 0; i < omm->nb_child; i++)
> +		clk_put(omm->child[i].clk);
> +
> +	return ret;
> +}
> +
> +static void stm32_omm_remove(struct platform_device *pdev)
> +{
> +	struct stm32_omm *omm = platform_get_drvdata(pdev);
> +	int i;
> +
> +	for (i = 0; i < omm->nb_child; i++)
> +		if (omm->child[i].dev)
> +			of_platform_device_destroy(omm->child[i].dev, NULL);
> +
> +	if (omm->cr & CR_MUXEN)
> +		stm32_omm_enable_child_clock(&pdev->dev, false);
> +
> +	pm_runtime_disable(&pdev->dev);

Should we have:
	for (i = 0; i < omm->nb_child; i++)
		clk_put(omm->child[i].clk);
as done in the error handling path of the probe?

> +}
> +
> +static const struct of_device_id stm32_omm_of_match[] = {
> +	{ .compatible = "st,stm32mp25-omm", },
> +	{},

Nitpick: Unneeded , after a terminator.

> +};
> +MODULE_DEVICE_TABLE(of, stm32_omm_of_match);

...

CJ