RE: [PATCH V2 2/4] nvmem: imx: add i.MX8 nvmem driver

[Peng Fan]

Hi Aisheng,

> Subject: RE: [PATCH V2 2/4] nvmem: imx: add i.MX8 nvmem driver
> 
> > From: Peng Fan
> > Sent: Wednesday, May 8, 2019 10:56 AM
> >
> > This patch adds i.MX8 nvmem ocotp driver to access fuse via RPC to
> > i.MX8 system controller.
> >
> > Cc: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> > Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
> > Cc: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> > Cc: Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx>
> > Cc: Fabio Estevam <festevam@xxxxxxxxx>
> > Cc: NXP Linux Team <linux-imx@xxxxxxx>
> > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> > ---
> >
> > V2:
> >  Add "scu" or "SCU", Add imx_sc_misc_otp_fuse_read, minor fixes
> >
> >  drivers/nvmem/Kconfig         |   7 ++
> >  drivers/nvmem/Makefile        |   2 +
> >  drivers/nvmem/imx-ocotp-scu.c | 170
> > ++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 179 insertions(+)
> >  create mode 100644 drivers/nvmem/imx-ocotp-scu.c
> >
> > diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig index
> > 530d570724c9..79afe44195a1 100644
> > --- a/drivers/nvmem/Kconfig
> > +++ b/drivers/nvmem/Kconfig
> > @@ -36,6 +36,13 @@ config NVMEM_IMX_OCOTP
> >  	  This driver can also be built as a module. If so, the module
> >  	  will be called nvmem-imx-ocotp.
> >
> > +config NVMEM_IMX_OCOTP_SCU
> > +	tristate "i.MX8 SCU On-Chip OTP Controller support"
> > +	depends on IMX_SCU
> > +	help
> > +	  This is a driver for the SCU On-Chip OTP Controller (OCOTP)
> > +	  available on i.MX8 SoCs.
> > +
> >  config NVMEM_LPC18XX_EEPROM
> >  	tristate "NXP LPC18XX EEPROM Memory Support"
> >  	depends on ARCH_LPC18XX || COMPILE_TEST diff --git
> > a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile index
> > 2ece8ffffdda..30d653d34e57 100644
> > --- a/drivers/nvmem/Makefile
> > +++ b/drivers/nvmem/Makefile
> > @@ -13,6 +13,8 @@ obj-$(CONFIG_NVMEM_IMX_IIM)	+=
> > nvmem-imx-iim.o
> >  nvmem-imx-iim-y			:= imx-iim.o
> >  obj-$(CONFIG_NVMEM_IMX_OCOTP)	+= nvmem-imx-ocotp.o
> >  nvmem-imx-ocotp-y		:= imx-ocotp.o
> > +obj-$(CONFIG_NVMEM_IMX_OCOTP_SCU)	+= nvmem-imx-ocotp-scu.o
> > +nvmem-imx-ocotp-scu-y		:= imx-ocotp-scu.o
> >  obj-$(CONFIG_NVMEM_LPC18XX_EEPROM)	+=
> > nvmem_lpc18xx_eeprom.o
> >  nvmem_lpc18xx_eeprom-y	:= lpc18xx_eeprom.o
> >  obj-$(CONFIG_NVMEM_LPC18XX_OTP)	+= nvmem_lpc18xx_otp.o
> > diff --git a/drivers/nvmem/imx-ocotp-scu.c
> > b/drivers/nvmem/imx-ocotp-scu.c new file mode 100644 index
> > 000000000000..038e744c8588
> > --- /dev/null
> > +++ b/drivers/nvmem/imx-ocotp-scu.c
> > @@ -0,0 +1,170 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * i.MX8 OCOTP fusebox driver
> > + *
> > + * Copyright 2019 NXP
> > + *
> > + * Peng Fan <peng.fan@xxxxxxx>
> > + */
> > +
> > +#include <linux/firmware/imx/sci.h>
> > +#include <linux/module.h>
> > +#include <linux/nvmem-provider.h>
> > +#include <linux/of_device.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +
> > +enum ocotp_devtype {
> > +	IMX8QXP,
> > +};
> > +
> > +struct ocotp_devtype_data {
> > +	int devtype;
> > +	int nregs;
> > +};
> > +
> > +struct ocotp_priv {
> > +	struct device *dev;
> > +	const struct ocotp_devtype_data *data;
> > +	struct imx_sc_ipc *nvmem_ipc;
> > +};
> > +
> > +struct imx_sc_msg_req_misc_fuse_read {
> > +	struct imx_sc_rpc_msg hdr;
> > +	u32 word;
> > +} __packed;
> > +
> > +struct imx_sc_msg_resp_misc_fuse_read {
> > +	struct imx_sc_rpc_msg hdr;
> > +	u32 val;
> > +} __packed;
> > +
> 
> How about
> struct imx_sc_msg_misc_fuse_read {
> 	struct imx_sc_rpc_msg hdr;
> 	union {
> 		u32 word;
> 		u32 val;
> 	} data;
> } __packed;

Then no need union, just "word" is ok here.
Fix in V3.

> 
> Then we can save one struct and convert.
> 
> > +static struct ocotp_devtype_data imx8qxp_data = {
> > +	.devtype = IMX8QXP,
> > +	.nregs = 800,
> > +};
> > +
> > +static int imx_sc_misc_otp_fuse_read(struct imx_sc_ipc *ipc, u32 word,
> > +				     u32 *val)
> > +{
> > +	struct imx_sc_msg_req_misc_fuse_read msg;
> > +	struct imx_sc_msg_resp_misc_fuse_read *resp;
> > +	struct imx_sc_rpc_msg *hdr = &msg.hdr;
> > +	int ret;
> > +
> > +	hdr->ver = IMX_SC_RPC_VERSION;
> > +	hdr->svc = (uint8_t)IMX_SC_RPC_SVC_MISC;
> > +	hdr->func = (uint8_t)IMX_SC_MISC_FUNC_OTP_FUSE_READ;
> 
> Pls drop the unnecessary type conversion.

Ok.

> 
> > +	hdr->size = 2;
> > +
> > +	msg.word = word;
> > +
> > +	ret = imx_scu_call_rpc(ipc, &msg, true);
> > +	if (ret)
> > +		return ret;
> > +
> > +	resp = (struct imx_sc_msg_resp_misc_fuse_read *)&msg;
> > +	if (val != NULL)
> 
> Drop this unnecessary check

ok.

> 
> > +		*val = resp->val;
> > +
> > +	return 0;
> > +}
> > +
> > +static int imx_scu_ocotp_read(void *context, unsigned int offset,
> > +			      void *val, size_t bytes)
> > +{
> > +	struct ocotp_priv *priv = context;
> > +	u32 count, index, num_bytes;
> > +	u32 *buf;
> > +	void *p;
> > +	int i, ret;
> > +
> > +	index = offset >> 2;
> > +	num_bytes = round_up((offset % 4) + bytes, 4);
> > +	count = num_bytes >> 2;
> > +
> > +	if (count > (priv->data->nregs - index))
> > +		count = priv->data->nregs - index;
> > +
> > +	p = kzalloc(num_bytes, GFP_KERNEL);
> > +	if (!p)
> > +		return -ENOMEM;
> > +
> > +	buf = p;
> > +
> > +	for (i = index; i < (index + count); i++) {
> > +		if (priv->data->devtype == IMX8QXP) {
> > +			if ((i > 271) && (i < 544)) {
> > +				*(u32 *)buf = 0;
> 
> Still need convert?

Will drop the convert.

> 
> > +				buf += 4;
> 
> I'm not sure this is right
> Shouldn't it be buf++ ?

You are right. Forget the fix the hole part.

> 
> > +				continue;
> > +			}
> > +		}
> > +
> > +		ret = imx_sc_misc_otp_fuse_read(priv->nvmem_ipc, i, buf);
> > +		if (ret) {
> > +			kfree(p);
> > +			return ret;
> > +		}
> > +		buf++;
> > +	}
> > +
> > +	memcpy(val, p + offset % 4, bytes);
> 
> Is there a build warning?
> I wonder a more safe way maybe:
> memcpy(val, (u8 *)p + offset % 4, byptes);

I did not meet issue. Fix in v3.

Thanks,
Peng.

> 
> Regards
> Dong Aisheng
> 
> > +
> > +	kfree(p);
> > +
> > +	return 0;
> > +}
> > +
> > +static struct nvmem_config imx_scu_ocotp_nvmem_config = {
> > +	.name = "imx-scu-ocotp",
> > +	.read_only = true,
> > +	.word_size = 4,
> > +	.stride = 1,
> > +	.owner = THIS_MODULE,
> > +	.reg_read = imx_scu_ocotp_read,
> > +};
> > +
> > +static const struct of_device_id imx_scu_ocotp_dt_ids[] = {
> > +	{ .compatible = "fsl,imx8qxp-scu-ocotp", (void *)&imx8qxp_data },
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, imx_scu_ocotp_dt_ids);
> > +
> > +static int imx_scu_ocotp_probe(struct platform_device *pdev) {
> > +	struct device *dev = &pdev->dev;
> > +	struct ocotp_priv *priv;
> > +	struct nvmem_device *nvmem;
> > +	int ret;
> > +
> > +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> > +	if (!priv)
> > +		return -ENOMEM;
> > +
> > +	ret = imx_scu_get_handle(&priv->nvmem_ipc);
> > +	if (ret)
> > +		return ret;
> > +
> > +	priv->data = of_device_get_match_data(dev);
> > +	priv->dev = dev;
> > +	imx_scu_ocotp_nvmem_config.size = 4 * priv->data->nregs;
> > +	imx_scu_ocotp_nvmem_config.dev = dev;
> > +	imx_scu_ocotp_nvmem_config.priv = priv;
> > +	nvmem = devm_nvmem_register(dev, &imx_scu_ocotp_nvmem_config);
> > +
> > +	return PTR_ERR_OR_ZERO(nvmem);
> > +}
> > +
> > +static struct platform_driver imx_scu_ocotp_driver = {
> > +	.probe	= imx_scu_ocotp_probe,
> > +	.driver = {
> > +		.name	= "imx_scu_ocotp",
> > +		.of_match_table = imx_scu_ocotp_dt_ids,
> > +	},
> > +};
> > +module_platform_driver(imx_scu_ocotp_driver);
> > +
> > +MODULE_AUTHOR("Peng Fan <peng.fan@xxxxxxx>");
> > +MODULE_DESCRIPTION("i.MX8 SCU OCOTP fuse box driver");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.16.4