[v5,2/2] nvmem: sec-qfprom: Add Qualcomm secure QFPROM support

For some of the Qualcomm SoC's, it is possible that
some of the fuse regions or entire qfprom region is
protected from non-secure access. In such situations,
Linux will have to use secure calls to read the region.
With that motivation, add secure qfprom driver.

Signed-off-by: Komal Bajaj <quic_kbajaj@quicinc.com>
---
 drivers/nvmem/Kconfig      |  13 +++++
 drivers/nvmem/Makefile     |   2 +
 drivers/nvmem/sec-qfprom.c | 101 +++++++++++++++++++++++++++++++++++++
 3 files changed, 116 insertions(+)
 create mode 100644 drivers/nvmem/sec-qfprom.c

--
2.40.1

On 7/27/2023 4:14 PM, Srinivas Kandagatla wrote:
> 
> 
> On 24/07/2023 09:38, Komal Bajaj wrote:
>> For some of the Qualcomm SoC's, it is possible that
>> some of the fuse regions or entire qfprom region is
>> protected from non-secure access. In such situations,
>> Linux will have to use secure calls to read the region.
>> With that motivation, add secure qfprom driver.
>>
>> Signed-off-by: Komal Bajaj <quic_kbajaj@quicinc.com>
>> ---
>>   drivers/nvmem/Kconfig      |  13 +++++
>>   drivers/nvmem/Makefile     |   2 +
>>   drivers/nvmem/sec-qfprom.c | 101 +++++++++++++++++++++++++++++++++++++
>>   3 files changed, 116 insertions(+)
>>   create mode 100644 drivers/nvmem/sec-qfprom.c
>>
> 
>> diff --git a/drivers/nvmem/sec-qfprom.c b/drivers/nvmem/sec-qfprom.c
>> new file mode 100644
>> index 000000000000..bc68053b7d94
>> --- /dev/null
>> +++ b/drivers/nvmem/sec-qfprom.c
>> @@ -0,0 +1,101 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights 
>> reserved.
>> + */
>> +
>> +#include <linux/firmware/qcom/qcom_scm.h>
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/nvmem-provider.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_runtime.h>
> 
>> +
>> +static int sec_qfprom_probe(struct platform_device *pdev)
>> +{
>> +    struct nvmem_config econfig = {
>> +        .name = "sec-qfprom",
>> +        .stride = 1,
>> +        .word_size = 1,
>> +        .id = NVMEM_DEVID_AUTO,
>> +        .reg_read = sec_qfprom_reg_read,
>> +    };
>> +    struct device *dev = &pdev->dev;
>> +    struct nvmem_device *nvmem;
>> +    struct sec_qfprom *priv;
>> +    struct resource *res;
>> +    int ret;
>> +
>> +    priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> +    if (!priv)
>> +        return -ENOMEM;
>> +
>> +    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +    if (!res)
>> +        return -EINVAL;
>> +
>> +    priv->base = res->start;
>> +
>> +    econfig.size = resource_size(res);
>> +    econfig.dev = dev;
>> +    econfig.priv = priv;
>> +
>> +    priv->dev = dev;
>> +
>> +    ret = devm_pm_runtime_enable(dev);
>> +    if (ret)
>> +        return ret;
> 
> Any reason why we need to enable pm runtime for this driver? As Am not 
> seeing any pm runtime handlers or users in this driver.

Thanks..
Yes, it is not needed as of now..
looks like, it got inherited from qfprom.c by mistake.

Same need to be corrected in Device tree, if any
unnecessary reference is there related to this..

-Mukesh
> 
> 
> --srini
>> +
>> +    nvmem = devm_nvmem_register(dev, &econfig);
>> +
>> +    return PTR_ERR_OR_ZERO(nvmem);
>> +}
>> +
>> +static const struct of_device_id sec_qfprom_of_match[] = {
>> +    { .compatible = "qcom,sec-qfprom" },
>> +    {/* sentinel */},
>> +};
>> +MODULE_DEVICE_TABLE(of, sec_qfprom_of_match);
>> +
>> +static struct platform_driver qfprom_driver = {
>> +    .probe = sec_qfprom_probe,
>> +    .driver = {
>> +        .name = "qcom_sec_qfprom",
>> +        .of_match_table = sec_qfprom_of_match,
>> +    },
>> +};
>> +module_platform_driver(qfprom_driver);
>> +MODULE_DESCRIPTION("Qualcomm Secure QFPROM driver");
>> +MODULE_LICENSE("GPL");
>> -- 
>> 2.40.1
>>

On 7/31/2023 10:05 PM, Bjorn Andersson wrote:
> On Thu, Jul 27, 2023 at 12:09:07PM +0530, Mukesh Ojha wrote:
>> On 7/24/2023 2:08 PM, Komal Bajaj wrote:
> [..]
>>> diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
>>> index f82431ec8aef..e248d3daadf3 100644
>>> --- a/drivers/nvmem/Makefile
>>> +++ b/drivers/nvmem/Makefile
>>> @@ -44,6 +44,8 @@ obj-$(CONFIG_NVMEM_NINTENDO_OTP)	+= nvmem-nintendo-otp.o
>>>    nvmem-nintendo-otp-y			:= nintendo-otp.o
>>>    obj-$(CONFIG_NVMEM_QCOM_QFPROM)		+= nvmem_qfprom.o
>>>    nvmem_qfprom-y				:= qfprom.o
>>> +obj-$(CONFIG_NVMEM_QCOM_SEC_QFPROM)	+= nvmem_sec_qfprom.o
>>> +nvmem_sec_qfprom-y			:= sec-qfprom.o
>> Are we just doing this for just renaming the object ?
>>
> Correct.
>
>>>    obj-$(CONFIG_NVMEM_RAVE_SP_EEPROM)	+= nvmem-rave-sp-eeprom.o
>>>    nvmem-rave-sp-eeprom-y			:= rave-sp-eeprom.o
>>>    obj-$(CONFIG_NVMEM_RMEM) 		+= nvmem-rmem.o
>>> diff --git a/drivers/nvmem/sec-qfprom.c b/drivers/nvmem/sec-qfprom.c
> [..]
>>> +static int sec_qfprom_reg_read(void *context, unsigned int reg, void *_val, size_t bytes)
>>> +{
>>> +	struct sec_qfprom *priv = context;
>>> +	unsigned int i;
>>> +	u8 *val = _val;
>>> +	u32 read_val;
>>> +	u8 *tmp;
>>> +
>>> +	for (i = 0; i < bytes; i++, reg++) {
>>> +		if (i == 0 || reg % 4 == 0) {
>>> +			if (qcom_scm_io_readl(priv->base + (reg & ~3), &read_val)) {
>>> +				dev_err(priv->dev, "Couldn't access fuse register\n");
>>> +				return -EINVAL;
>>> +			}
>>> +			tmp = (u8 *)&read_val;
>>> +		}
>>> +
>>> +		val[i] = tmp[reg & 3];
>>> +	}
>> Getting secure read from fuse region is fine here, since we have to read
>> 4 byte from trustzone, but this restriction of reading is also there
>> for sm8{4|5}50 soc's where byte by byte reading is protected and granularity
>> set to 4 byte (qfprom_reg_read() in drivers/nvmem/qfprom.c)
>> is will result in abort, in  that case this function need to export this
>> logic.
>>
> If qfprom needs similar treatment, then let's land this first and then
> consider generalizing (i.e. move to some library code) this - or if
> infeasible, just fix qfprom_reg_read().

Agree, I will implement this logic into qfprom driver (into 
qfprom_reg_read() ) in a separate patch.

Thanks
Komal
>
> Regards,
> Bjorn