Sender: Guenter Roeck <groeck7@gmail.com>
Date:   Fri, 17 Mar 2023 07:16:33 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Tomer Maimon <tmaimon77@gmail.com>
Cc:     ulf.hansson@linaro.org, avifishman70@gmail.com,
        tali.perry1@gmail.com, joel@jms.id.au, venture@google.com,
        yuenn@google.com, benjaminfair@google.com, adrian.hunter@intel.com,
        skhan@linuxfoundation.org, davidgow@google.com,
        pbrobinson@gmail.com, gsomlo@gmail.com, briannorris@chromium.org,
        arnd@arndb.de, krakoczy@antmicro.com, andy.shevchenko@gmail.com,
        openbmc@lists.ozlabs.org, linux-mmc@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] mmc: sdhci-npcm: Add NPCM SDHCI driver
Message-ID: <f28c7c34-077c-4c7e-afd8-c4180718d403@roeck-us.net>
References: <20221205085351.27566-1-tmaimon77@gmail.com>
 <20221205085351.27566-3-tmaimon77@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20221205085351.27566-3-tmaimon77@gmail.com>
Precedence: bulk

On Mon, Dec 05, 2022 at 10:53:51AM +0200, Tomer Maimon wrote:
> Add Nuvoton NPCM BMC sdhci-pltfm controller driver.
> 
> Signed-off-by: Tomer Maimon <tmaimon77@gmail.com>

I still don't see this driver in the upstream kernel, or in linux-next.

Couple of comments:

- devm ordering does not really matter here. The devm resource
  is the clock, it does not depend on local data, and it will be
  released last, so that is ok.
- sdhci_pltfm_unregister() calls clk_disable_unprepare(),
  so there is no enabled clock floating around on driver removal.
  Unfortunately, that also means that the more convenient
  devm_clk_get_optional_enabled() can not be used.

Real problem inline below.

Guenter

> ---
>  drivers/mmc/host/Kconfig      |  8 ++++
>  drivers/mmc/host/Makefile     |  1 +
>  drivers/mmc/host/sdhci-npcm.c | 84 +++++++++++++++++++++++++++++++++++
>  3 files changed, 93 insertions(+)
>  create mode 100644 drivers/mmc/host/sdhci-npcm.c
> 
> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> index fb1062a6394c..82ab6fc25dca 100644
> --- a/drivers/mmc/host/Kconfig
> +++ b/drivers/mmc/host/Kconfig
> @@ -415,6 +415,14 @@ config MMC_SDHCI_MILBEAUT
>  
>  	  If unsure, say N.
>  
> +config MMC_SDHCI_NPCM
> +	tristate "Secure Digital Host Controller Interface support for NPCM"
> +	depends on ARCH_NPCM || COMPILE_TEST
> +	depends on MMC_SDHCI_PLTFM
> +	help
> +	  This provides support for the SD/eMMC controller found in
> +	  NPCM BMC family SoCs.
> +
>  config MMC_SDHCI_IPROC
>  	tristate "SDHCI support for the BCM2835 & iProc SD/MMC Controller"
>  	depends on ARCH_BCM2835 || ARCH_BCM_IPROC || ARCH_BRCMSTB || COMPILE_TEST
> diff --git a/drivers/mmc/host/Makefile b/drivers/mmc/host/Makefile
> index 4e4ceb32c4b4..a101f87a5f19 100644
> --- a/drivers/mmc/host/Makefile
> +++ b/drivers/mmc/host/Makefile
> @@ -97,6 +97,7 @@ obj-$(CONFIG_MMC_SDHCI_MICROCHIP_PIC32)	+= sdhci-pic32.o
>  obj-$(CONFIG_MMC_SDHCI_BRCMSTB)		+= sdhci-brcmstb.o
>  obj-$(CONFIG_MMC_SDHCI_OMAP)		+= sdhci-omap.o
>  obj-$(CONFIG_MMC_SDHCI_SPRD)		+= sdhci-sprd.o
> +obj-$(CONFIG_MMC_SDHCI_NPCM)		+= sdhci-npcm.o
>  obj-$(CONFIG_MMC_CQHCI)			+= cqhci.o
>  cqhci-y					+= cqhci-core.o
>  cqhci-$(CONFIG_MMC_CRYPTO)		+= cqhci-crypto.o
> diff --git a/drivers/mmc/host/sdhci-npcm.c b/drivers/mmc/host/sdhci-npcm.c
> new file mode 100644
> index 000000000000..beace15b6c00
> --- /dev/null
> +++ b/drivers/mmc/host/sdhci-npcm.c
> @@ -0,0 +1,84 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * NPCM SDHC MMC host controller driver.
> + *
> + * Copyright (c) 2020 Nuvoton Technology corporation.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/mmc/host.h>
> +#include <linux/mmc/mmc.h>
> +#include <linux/module.h>
> +
> +#include "sdhci-pltfm.h"
> +
> +static const struct sdhci_pltfm_data npcm_sdhci_pdata = {
> +	.quirks  = SDHCI_QUIRK_DELAY_AFTER_POWER,
> +	.quirks2 = SDHCI_QUIRK2_STOP_WITH_TC |
> +		   SDHCI_QUIRK2_NO_1_8_V,
> +};
> +
> +static int npcm_sdhci_probe(struct platform_device *pdev)
> +{
> +	struct sdhci_pltfm_host *pltfm_host;
> +	struct sdhci_host *host;
> +	u32 caps;
> +	int ret;
> +
> +	host = sdhci_pltfm_init(pdev, &npcm_sdhci_pdata, 0);
> +	if (IS_ERR(host))
> +		return PTR_ERR(host);
> +
> +	pltfm_host = sdhci_priv(host);
> +
> +	pltfm_host->clk = devm_clk_get_optional(&pdev->dev, NULL);
> +	if (IS_ERR(pltfm_host->clk))
> +		return PTR_ERR(pltfm_host->clk);
> +
> +	ret = clk_prepare_enable(pltfm_host->clk);
> +	if (ret)
> +		return ret;
> +

The two functions above should not return but goto the call
to sdhci_pltfm_free() to avoid a memory leak on error.

> +	caps = sdhci_readl(host, SDHCI_CAPABILITIES);
> +	if (caps & SDHCI_CAN_DO_8BIT)
> +		host->mmc->caps |= MMC_CAP_8_BIT_DATA;
> +
> +	ret = mmc_of_parse(host->mmc);
> +	if (ret)
> +		goto err_sdhci_add;
> +
> +	ret = sdhci_add_host(host);
> +	if (ret)
> +		goto err_sdhci_add;
> +
> +	return 0;
> +
> +err_sdhci_add:
> +	clk_disable_unprepare(pltfm_host->clk);
> +	sdhci_pltfm_free(pdev);
> +	return ret;
> +}
> +
> +static const struct of_device_id npcm_sdhci_of_match[] = {
> +	{ .compatible = "nuvoton,npcm750-sdhci" },
> +	{ .compatible = "nuvoton,npcm845-sdhci" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, npcm_sdhci_of_match);
> +
> +static struct platform_driver npcm_sdhci_driver = {
> +	.driver = {
> +		.name	= "npcm-sdhci",
> +		.of_match_table = npcm_sdhci_of_match,
> +		.pm	= &sdhci_pltfm_pmops,
> +	},
> +	.probe		= npcm_sdhci_probe,
> +	.remove		= sdhci_pltfm_unregister,
> +};
> +module_platform_driver(npcm_sdhci_driver);
> +
> +MODULE_DESCRIPTION("NPCM Secure Digital Host Controller Interface driver");
> +MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>");
> +MODULE_LICENSE("GPL");
> -- 
> 2.33.0
>