| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <b885eeb5-1542-775f-ab7b-b1218c6a337a@baylibre.com>
Date: Wed, 13 May 2020 14:33:29 +0200
From: Neil Armstrong <narmstrong@...libre.com>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc: linux-amlogic@...ts.infradead.org, linux-pm@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/6] nvmem: add support for the Khadas MCU Programmable
User Memory
On 13/05/2020 12:34, Srinivas Kandagatla wrote:
>
>
> On 12/05/2020 14:26, Neil Armstrong wrote:
>> The new Khadas VIM2, VIM3 and Edge boards embeds an on-board microcontroller
>> offering a 56bytes User Programmable NVMEM array.
>>
>> This array needs a password to be writable, thus a password sysfs file
>> has been added on the device node to unlock the NVMEM.
>
> Is this one time programmable? Or does it need to be unlocked for every read/write?
It can be rewritten, and needs the password to read & write.
>
> How can you make sure that the memory is unlocked before making attempt to read/write?
The only way to know it's unlock is reading back the password when unlocked.
>
>>
>> The default 6bytes password id: "Khadas"
>>
>> This implements the user NVMEM devices as cell of the Khadas MCU MFD driver.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>> ---
>> drivers/nvmem/Kconfig | 8 ++
>> drivers/nvmem/Makefile | 2 +
>> drivers/nvmem/khadas-mcu-user-mem.c | 128 ++++++++++++++++++++++++++++
>> 3 files changed, 138 insertions(+)
>> create mode 100644 drivers/nvmem/khadas-mcu-user-mem.c
>>
>> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
>> index d7b7f6d688e7..92cd4f6aa931 100644
>> --- a/drivers/nvmem/Kconfig
>> +++ b/drivers/nvmem/Kconfig
>> @@ -67,6 +67,14 @@ config JZ4780_EFUSE
>> To compile this driver as a module, choose M here: the module
>> will be called nvmem_jz4780_efuse.
>> +config NVMEM_KHADAS_MCU_USER_MEM
>> + tristate "Khadas MCU User programmable memory support"
>> + depends on MFD_KHADAS_MCU
>> + depends on REGMAP
>> + help
>> + This is a driver for the MCU User programmable memory
>> + available on the Khadas VIM and Edge boards.
>> +
>> 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 a7c377218341..0516a309542d 100644
>> --- a/drivers/nvmem/Makefile
>> +++ b/drivers/nvmem/Makefile
>> @@ -17,6 +17,8 @@ obj-$(CONFIG_NVMEM_IMX_OCOTP_SCU) += nvmem-imx-ocotp-scu.o
>> nvmem-imx-ocotp-scu-y := imx-ocotp-scu.o
>> obj-$(CONFIG_JZ4780_EFUSE) += nvmem_jz4780_efuse.o
>> nvmem_jz4780_efuse-y := jz4780-efuse.o
>> +obj-$(CONFIG_NVMEM_KHADAS_MCU_USER_MEM) += nvmem-khadas-mcu-user-mem.o
>> +nvmem-khadas-mcu-user-mem-y := khadas-mcu-user-mem.o
>> obj-$(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/khadas-mcu-user-mem.c b/drivers/nvmem/khadas-mcu-user-mem.c
>> new file mode 100644
>> index 000000000000..a1d5ae9a030c
>> --- /dev/null
>> +++ b/drivers/nvmem/khadas-mcu-user-mem.c
>> @@ -0,0 +1,128 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Driver for Khadas MCU User programmable Memory
>> + *
>> + * Copyright (C) 2020 BayLibre SAS
>> + * Author(s): Neil Armstrong <narmstrong@...libre.com>
>> + */
>> +
>> +#include <linux/clk.h>
>
> Why do we need this header?
Will drop
>
>> +#include <linux/module.h>
>> +#include <linux/nvmem-provider.h>
>> +#include <linux/mfd/khadas-mcu.h>
>> +#include <linux/regmap.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +
>> +static int khadas_mcu_user_mem_read(void *context, unsigned int offset,
>> + void *val, size_t bytes)
>> +{
>> + struct khadas_mcu *khadas_mcu = context;
>> +
>> + return regmap_bulk_read(khadas_mcu->map,
>> + KHADAS_MCU_USER_DATA_0_REG + offset,
>> + val, bytes);
>> +}
>> +
>> +static int khadas_mcu_user_mem_write(void *context, unsigned int offset,
>> + void *val, size_t bytes)
>> +{
>> + struct khadas_mcu *khadas_mcu = context;
>> +
>> + return regmap_bulk_write(khadas_mcu->map,
>> + KHADAS_MCU_USER_DATA_0_REG + offset,
>> + val, bytes);
>> +}
>> +
>> +static ssize_t password_store(struct device *dev, struct device_attribute *attr,
>> + const char *buf, size_t count)
>> +{
>> + struct khadas_mcu *khadas_mcu = dev_get_drvdata(dev);
>> + int i, ret;
>> +
>> + if (count < 6)
>> + return -EINVAL;
>
> Possibly this magic 6 value needs proper define. An additional check here for > 6 would be better as well.
Ok
>
>> +
>> + ret = regmap_write(khadas_mcu->map, KHADAS_MCU_PASSWD_START_REG, 1);
>> + if (ret)
>> + return ret;
>> +
>> + for (i = 0 ; i < 6 ; ++i) {
>> + ret = regmap_write(khadas_mcu->map,
>> + KHADAS_MCU_CHECK_USER_PASSWD_REG,
>> + buf[i]);
>> + if (ret)
>> + goto out;
>> + }
>> +
>> + ret = regmap_write(khadas_mcu->map, KHADAS_MCU_PASSWD_START_REG, 0);
>> + if (ret)
>> + return ret;
>> +
>> + return count;
>> +out:
>> + regmap_write(khadas_mcu->map, KHADAS_MCU_PASSWD_START_REG, 0);
>> +
>> + return ret;
>> +}
>> +
>> +static DEVICE_ATTR_WO(password);
>> +
>> +static struct attribute *khadas_mcu_user_mem_sysfs_attributes[] = {
>> + &dev_attr_password.attr,
>> + NULL,
>> +};
>> +
>> +static const struct attribute_group khadas_mcu_user_mem_sysfs_attr_group = {
>> + .attrs = khadas_mcu_user_mem_sysfs_attributes,
>> +};
>> +
>> +static int khadas_mcu_user_mem_probe(struct platform_device *pdev)
>> +{
>> + struct khadas_mcu *khadas_mcu = dev_get_drvdata(pdev->dev.parent);
>
> You could probably get away with dependency of this structure and the header itself by directly getting hold of regmap from parent device.
Ok
>
>
>> + struct device *dev = &pdev->dev;
>> + struct nvmem_device *nvmem;
>> + struct nvmem_config *econfig;
>> +
>> + econfig = devm_kzalloc(dev, sizeof(*econfig), GFP_KERNEL);
>> + if (!econfig)
>> + return -ENOMEM;
>> +
>> + econfig->dev = pdev->dev.parent;
>> + econfig->name = dev_name(pdev->dev.parent);
>> + econfig->stride = 1;
>> + econfig->word_size = 1;
>> + econfig->reg_read = khadas_mcu_user_mem_read;
>> + econfig->reg_write = khadas_mcu_user_mem_write;
>> + econfig->size = 56;
> define 56 to make it more readable!
Ok
>
>> + econfig->priv = khadas_mcu;
>> +
>> + platform_set_drvdata(pdev, khadas_mcu);
>> +
>> + nvmem = devm_nvmem_register(&pdev->dev, econfig);
>> + if (IS_ERR(nvmem))
>> + return PTR_ERR(nvmem);
>> +
>> + return sysfs_create_group(&pdev->dev.kobj,
>> + &khadas_mcu_user_mem_sysfs_attr_group);
>> +}
>> +
>> +static const struct platform_device_id khadas_mcu_user_mem_id_table[] = {
>> + { .name = "khadas-mcu-user-mem", },
>> + {},
>> +};
>> +MODULE_DEVICE_TABLE(platform, khadas_mcu_user_mem_id_table);
>> +
>> +static struct platform_driver khadas_mcu_user_mem_driver = {
>> + .probe = khadas_mcu_user_mem_probe,
>> + .driver = {
>> + .name = "khadas-mcu-user-mem",
>> + },
>> + .id_table = khadas_mcu_user_mem_id_table,
>> +};
>> +
>> +module_platform_driver(khadas_mcu_user_mem_driver);
>> +
>> +MODULE_AUTHOR("Neil Armstrong <narmstrong@...libre.com>");
>> +MODULE_DESCRIPTION("Khadas MCU User MEM driver");
>> +MODULE_LICENSE("GPL v2");
>>
Thanks for the review.
Neil
Powered by blists - more mailing lists