linux-kernel - Re: [PATCH v10 char-misc-next 1/2] misc: microchip: pci1xxxx: Add support to read and write into PCI1XXXX OTP via NVMEM sysfs

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Date:   Tue, 25 Apr 2023 09:33:40 +0200
From:   Michael Walle <michael@...le.cc>
To:     "Vaibhaav Ram T.L" <vaibhaavram.tl@...rochip.com>
Cc:     gregkh@...uxfoundation.org, arnd@...db.de,
        kumaravel.thiagarajan@...rochip.com,
        tharunkumar.pasumarthi@...rochip.com, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org, UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH v10 char-misc-next 1/2] misc: microchip: pci1xxxx: Add
 support to read and write into PCI1XXXX OTP via NVMEM sysfs

Hi,

> +static int pci1xxxx_otp_read(void *priv_t, unsigned int off,
> +			     void *buf_t, size_t count)
> +{
> +	struct pci1xxxx_otp_eeprom_device *priv = priv_t;
> +	void __iomem *rb = priv->reg_base;
> +	char *buf = buf_t;
> +	u32 regval;
> +	u32 byte;
> +	int ret;
> +	u8 data;
> +
> +	if (off >= priv->nvmem_config_otp.size)
> +		return -EFAULT;
> +
> +	if ((off + count) > priv->nvmem_config_otp.size)
> +		count = priv->nvmem_config_otp.size - off;
> +
> +	ret = set_sys_lock(priv);
> +	if (ret)
> +		return ret;
> +
> +	for (byte = 0; byte < count; byte++) {
> +		otp_device_set_address(priv, (u16)(off + byte));
> +		data = readl(rb + MMAP_OTP_OFFSET(OTP_FUNC_CMD_OFFSET));
> +		writel(data | OTP_FUNC_RD_BIT,
> +		       rb + MMAP_OTP_OFFSET(OTP_FUNC_CMD_OFFSET));
> +		data = readl(rb + MMAP_OTP_OFFSET(OTP_CMD_GO_OFFSET));
> +		writel(data | OTP_CMD_GO_BIT,
> +		       rb + MMAP_OTP_OFFSET(OTP_CMD_GO_OFFSET));
> +
> +		ret = read_poll_timeout(readl, regval,
> +					!(regval & OTP_STATUS_BUSY_BIT),
> +					STATUS_READ_DELAY_US,
> +					STATUS_READ_TIMEOUT_US, true,
> +					rb + MMAP_OTP_OFFSET(OTP_STATUS_OFFSET));
> +
> +		data = readl(rb + MMAP_OTP_OFFSET(OTP_PASS_FAIL_OFFSET));
> +		if (ret < 0 || data & OTP_FAIL_BIT)
> +			return -EIO;

Don't you need to release the lock?

> +
> +		buf[byte] = readl(rb + MMAP_OTP_OFFSET(OTP_RD_DATA_OFFSET));
> +	}
> +	release_sys_lock(priv);
> +
> +	return byte;
> +}