Messages in this thread | | | Subject | Re: [PATCH v2 4/6] nvmem: add support for the Khadas MCU Programmable User Memory | From | Neil Armstrong <> | Date | Wed, 13 May 2020 14:33:29 +0200 |
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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@baylibre.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@baylibre.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@baylibre.com>"); >> +MODULE_DESCRIPTION("Khadas MCU User MEM driver"); >> +MODULE_LICENSE("GPL v2"); >>
Thanks for the review.
Neil
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