[PATCH v4 01/14] misc: add driver for the SiFive otp controller

Pragnesh Patel pragnesh.patel at sifive.com
Fri Mar 6 08:42:51 CET 2020 

Hi Palmer,

>-----Original Message-----
>From: Palmer Dabbelt <palmerdabbelt at google.com>
>Sent: 06 March 2020 06:07
>To: Pragnesh Patel <pragnesh.patel at sifive.com>
>Cc: u-boot at lists.denx.de; Atish Patra <Atish.Patra at wdc.com>;
>bmeng.cn at gmail.com; Paul Walmsley <paul.walmsley at sifive.com>;
>jagan at amarulasolutions.com; Troy Benjegerdes
><troy.benjegerdes at sifive.com>; Anup Patel <Anup.Patel at wdc.com>; Sagar
>Kadam <sagar.kadam at sifive.com>; Pragnesh Patel
><pragnesh.patel at sifive.com>; sjg at chromium.org; finley.xiao at rock-
>chips.com; marcel.ziswiler at toradex.com; t-kristo at ti.com;
>aford173 at gmail.com; peng.fan at nxp.com; eugen.hristev at microchip.com; j-
>keerthy at ti.com
>Subject: Re: [PATCH v4 01/14] misc: add driver for the SiFive otp controller
>
>On Mon, 24 Feb 2020 00:32:33 PST (-0800), pragnesh.patel at sifive.com wrote:
>> Added a misc driver to handle OTP memory in SiFive SoCs.
>>
>> Signed-off-by: Pragnesh Patel <pragnesh.patel at sifive.com>
>> ---
>>  drivers/misc/Kconfig      |   7 ++
>>  drivers/misc/Makefile     |   1 +
>>  drivers/misc/sifive-otp.c | 241
>> ++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 249 insertions(+)
>>  create mode 100644 drivers/misc/sifive-otp.c
>>
>> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index
>> f18aa8f7ba..fcb45c63d4 100644
>> --- a/drivers/misc/Kconfig
>> +++ b/drivers/misc/Kconfig
>> @@ -68,6 +68,13 @@ config ROCKCHIP_OTP
>>  	  addressing and a length or through child-nodes that are generated
>>  	  based on the e-fuse map retrieved from the DTS.
>>
>> +config SIFIVE_OTP
>> +	bool "SiFive Ememory OTP driver"
>> +	depends on RISCV && MISC
>> +	help
>> +	  Enable support for reading and writing the ememory OTP on the
>> +	  SiFive SoCs.
>> +
>>  config VEXPRESS_CONFIG
>>  	bool "Enable support for Arm Versatile Express config bus"
>>  	depends on MISC
>> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index
>> 2b843de93c..ee888631b6 100644
>> --- a/drivers/misc/Makefile
>> +++ b/drivers/misc/Makefile
>> @@ -58,6 +58,7 @@ obj-$(CONFIG_$(SPL_)PWRSEQ) += pwrseq-uclass.o
>>  obj-$(CONFIG_QFW) += qfw.o
>>  obj-$(CONFIG_ROCKCHIP_EFUSE) += rockchip-efuse.o
>>  obj-$(CONFIG_ROCKCHIP_OTP) += rockchip-otp.o
>> +obj-$(CONFIG_SIFIVE_OTP) += sifive-otp.o
>>  obj-$(CONFIG_SANDBOX) += syscon_sandbox.o misc_sandbox.o
>>  obj-$(CONFIG_SMSC_LPC47M) += smsc_lpc47m.o
>>  obj-$(CONFIG_SMSC_SIO1007) += smsc_sio1007.o diff --git
>> a/drivers/misc/sifive-otp.c b/drivers/misc/sifive-otp.c new file mode
>> 100644 index 0000000000..6a39ec42df
>> --- /dev/null
>> +++ b/drivers/misc/sifive-otp.c
>> @@ -0,0 +1,241 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * This is a driver for the eMemory EG004K32TQ028XW01 NeoFuse
>> + * One-Time-Programmable (OTP) memory used within the SiFive FU540.
>> + * It is documented in the FU540 manual here:
>> + *
>> +https://www.sifive.com/documentation/chips/freedom-u540-c000-
>manual/
>> + *
>> + * Copyright (C) 2018 Philipp Hug <philipp at hug.cx>
>> + * Copyright (C) 2018 Joey Hewitt <joey at joeyhewitt.com>
>> + *
>> + * Copyright (C) 2020 SiFive, Inc
>> + */
>> +
>> +/*
>> + * The FU540 stores 4096x32 bit (16KiB) values.
>> + * Index 0x00-0xff are reserved for SiFive internal use. (first 1KiB)
>> + * Right now first 1KB is used to store only serial number.
>> + */
>> +
>> +#include <common.h>
>> +#include <dm/device.h>
>> +#include <dm/read.h>
>> +#include <linux/io.h>
>> +#include <misc.h>
>> +
>> +#define BYTES_PER_FUSE		4
>> +
>> +#define PA_RESET_VAL		0x00
>> +#define PAS_RESET_VAL		0x00
>> +#define PAIO_RESET_VAL		0x00
>> +#define PDIN_RESET_VAL		0x00
>> +#define PTM_RESET_VAL		0x00
>> +
>> +#define PCLK_ENABLE_VAL			BIT(0)
>> +#define PCLK_DISABLE_VAL		0x00
>> +
>> +#define PWE_WRITE_ENABLE		BIT(0)
>> +#define PWE_WRITE_DISABLE		0x00
>> +
>> +#define PTM_FUSE_PROGRAM_VAL		BIT(1)
>> +
>> +#define PCE_ENABLE_INPUT		BIT(0)
>> +#define PCE_DISABLE_INPUT		0x00
>> +
>> +#define PPROG_ENABLE_INPUT		BIT(0)
>> +#define PPROG_DISABLE_INPUT		0x00
>> +
>> +#define PTRIM_ENABLE_INPUT		BIT(0)
>> +#define PTRIM_DISABLE_INPUT		0x00
>> +
>> +#define PDSTB_DEEP_STANDBY_ENABLE	BIT(0)
>> +#define PDSTB_DEEP_STANDBY_DISABLE	0x00
>> +
>> +struct sifive_otp_regs {
>> +	u32 pa;     /* Address input */
>> +	u32 paio;   /* Program address input */
>> +	u32 pas;    /* Program redundancy cell selection input */
>> +	u32 pce;    /* OTP Macro enable input */
>> +	u32 pclk;   /* Clock input */
>> +	u32 pdin;   /* Write data input */
>> +	u32 pdout;  /* Read data output */
>> +	u32 pdstb;  /* Deep standby mode enable input (active low) */
>> +	u32 pprog;  /* Program mode enable input */
>> +	u32 ptc;    /* Test column enable input */
>> +	u32 ptm;    /* Test mode enable input */
>> +	u32 ptm_rep;/* Repair function test mode enable input */
>> +	u32 ptr;    /* Test row enable input */
>> +	u32 ptrim;  /* Repair function enable input */
>> +	u32 pwe;    /* Write enable input (defines program cycle) */
>> +} __packed;
>> +
>> +struct sifive_otp_platdata {
>> +	struct sifive_otp_regs __iomem *regs;
>> +	u32 total_fuses;
>> +};
>> +
>> +/*
>> + * offset and size are assumed aligned to the size of the fuses (32bit).
>> + */
>> +static int sifive_otp_read(struct udevice *dev, int offset,
>> +			   void *buf, int size)
>> +{
>> +	struct sifive_otp_platdata *plat = dev_get_platdata(dev);
>> +	struct sifive_otp_regs *regs = (struct sifive_otp_regs *)plat->regs;
>> +
>> +	int fuseidx = offset / BYTES_PER_FUSE;
>> +	int fusecount = size / BYTES_PER_FUSE;
>> +	u32 fusebuf[fusecount];
>> +
>> +	/* check bounds */
>> +	if (offset < 0 || size < 0)
>> +		return -EINVAL;
>> +	if (fuseidx >= plat->total_fuses)
>> +		return -EINVAL;
>> +	if ((fuseidx + fusecount) > plat->total_fuses)
>> +		return -EINVAL;
>> +
>> +	/* init OTP */
>> +	iowrite32(PDSTB_DEEP_STANDBY_ENABLE, &regs->pdstb);
>> +	iowrite32(PTRIM_ENABLE_INPUT, &regs->ptrim);
>> +	iowrite32(PCE_ENABLE_INPUT, &regs->pce);
>> +
>> +	/* read all requested fuses */
>> +	for (unsigned int i = 0; i < fusecount; i++, fuseidx++) {
>> +		iowrite32(fuseidx, &regs->pa);
>> +
>> +		/* cycle clock to read */
>> +		iowrite32(PCLK_ENABLE_VAL, &regs->pclk);
>> +		mdelay(1);
>> +		iowrite32(PCLK_DISABLE_VAL, &regs->pclk);
>> +		mdelay(1);
>> +
>> +		/* read the value */
>> +		fusebuf[i] = ioread32(&regs->pdout);
>> +	}
>> +
>> +	/* shut down */
>> +	iowrite32(PCE_DISABLE_INPUT, &regs->pce);
>> +	iowrite32(PTRIM_DISABLE_INPUT, &regs->ptrim);
>> +	iowrite32(PDSTB_DEEP_STANDBY_DISABLE, &regs->pdstb);
>> +
>> +	// copy out
>> +	memcpy(buf, fusebuf, size);
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Caution:
>> + * OTP can be written only once, so use carefully.
>> + *
>> + * offset and size are assumed aligned to the size of the fuses (32bit).
>> + */
>> +static int sifive_otp_write(struct udevice *dev, int offset,
>> +			    const void *buf, int size)
>> +{
>> +	struct sifive_otp_platdata *plat = dev_get_platdata(dev);
>> +	struct sifive_otp_regs *regs = (struct sifive_otp_regs *)plat->regs;
>> +
>> +	int fuseidx = offset / BYTES_PER_FUSE;
>> +	int fusecount = size / BYTES_PER_FUSE;
>> +	u32 *write_buf = (u32 *)buf;
>> +	u32 write_data;
>> +	int i, pas, bit;
>> +
>> +	/* check bounds */
>> +	if (offset < 0 || size < 0)
>> +		return -EINVAL;
>> +	if (fuseidx >= plat->total_fuses)
>> +		return -EINVAL;
>> +	if ((fuseidx + fusecount) > plat->total_fuses)
>> +		return -EINVAL;
>> +
>> +	/* init OTP */
>> +	iowrite32(PDSTB_DEEP_STANDBY_ENABLE, &regs->pdstb);
>> +	iowrite32(PTRIM_ENABLE_INPUT, &regs->ptrim);
>> +
>> +	/* reset registers */
>> +	iowrite32(PCLK_DISABLE_VAL, &regs->pclk);
>> +	iowrite32(PA_RESET_VAL, &regs->pa);
>> +	iowrite32(PAS_RESET_VAL, &regs->pas);
>> +	iowrite32(PAIO_RESET_VAL, &regs->paio);
>> +	iowrite32(PDIN_RESET_VAL, &regs->pdin);
>> +	iowrite32(PWE_WRITE_DISABLE, &regs->pwe);
>> +	iowrite32(PTM_FUSE_PROGRAM_VAL, &regs->ptm);
>> +	mdelay(1);
>> +
>> +	iowrite32(PCE_ENABLE_INPUT, &regs->pce);
>> +	iowrite32(PPROG_ENABLE_INPUT, &regs->pprog);
>> +	iowrite32(PTRIM_ENABLE_INPUT, &regs->ptrim);
>> +
>> +	/* write all requested fuses */
>> +	for (i = 0; i < fusecount; i++, fuseidx++) {
>> +		iowrite32(fuseidx, &regs->pa);
>> +		write_data = *(write_buf++);
>> +
>> +		for (pas = 0; pas < 2; pas++) {
>> +			iowrite32(pas, &regs->pas);
>> +
>> +			for (bit = 0; bit < 32; bit++) {
>> +				iowrite32(bit, &regs->paio);
>> +				iowrite32(((write_data >> bit) & 1),
>> +					  &regs->pdin);
>> +				mdelay(1);
>> +
>> +				iowrite32(PWE_WRITE_ENABLE, &regs->pwe);
>> +				mdelay(1);
>> +				iowrite32(PWE_WRITE_DISABLE, &regs->pwe);
>> +				mdelay(1);
>
>IIRC, interrupting this sequence will cause irreversable damage to the chip.  I
>don't know u-boot well enough to know if this executes in a context that can
>be interrupted, though.

Thanks for pointing me to this.

As far as I know, u-boot is strictly single-threaded and all drivers use polling only.
https://lists.denx.de/pipermail/u-boot/2011-May/092772.html

Interrupts are not really used in U-Boot.
https://stackoverflow.com/questions/23491365/handling-gpio-interrupts-in-u-boot

So there is very less chances of this sequence will be interrupted.

>
>> +			}
>> +		}
>> +
>> +		iowrite32(PAS_RESET_VAL, &regs->pas);
>> +	}
>> +
>> +	/* shut down */
>> +	iowrite32(PWE_WRITE_DISABLE, &regs->pwe);
>> +	iowrite32(PPROG_DISABLE_INPUT, &regs->pprog);
>> +	iowrite32(PCE_DISABLE_INPUT, &regs->pce);
>> +	iowrite32(PTM_RESET_VAL, &regs->ptm);
>> +
>> +	iowrite32(PTRIM_DISABLE_INPUT, &regs->ptrim);
>> +	iowrite32(PDSTB_DEEP_STANDBY_DISABLE, &regs->pdstb);
>> +
>> +	return 0;
>> +}
>> +
>> +static int sifive_otp_ofdata_to_platdata(struct udevice *dev) {
>> +	struct sifive_otp_platdata *plat = dev_get_platdata(dev);
>> +	int ret;
>> +
>> +	plat->regs = dev_read_addr_ptr(dev);
>> +
>> +	ret = dev_read_u32(dev, "fuse-count", &plat->total_fuses);
>> +	if (ret < 0) {
>> +		pr_err("\"fuse-count\" not found\n");
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct misc_ops sifive_otp_ops = {
>> +	.read = sifive_otp_read,
>> +	.write = sifive_otp_write,
>> +};
>> +
>> +static const struct udevice_id sifive_otp_ids[] = {
>> +	{ .compatible = "sifive,fu540-otp" },
>> +	{}
>> +};
>> +
>> +U_BOOT_DRIVER(sifive_otp) = {
>> +	.name = "sifive_otp",
>> +	.id = UCLASS_MISC,
>> +	.of_match = sifive_otp_ids,
>> +	.ofdata_to_platdata = sifive_otp_ofdata_to_platdata,
>> +	.platdata_auto_alloc_size = sizeof(struct sifive_otp_platdata),
>> +	.ops = &sifive_otp_ops,
>> +};

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