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Date: Mon, 17 Feb 2020 11:58:34 -0300
From: Paul Cercueil <paul@...pouillou.net>
To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc: "H. Nikolaus Schaller" <hns@...delico.com>,
PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>,
Mathieu Malaterre <malat@...ian.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Ralf Baechle <ralf@...ux-mips.org>,
Paul Burton <paulburton@...nel.org>,
Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Krzysztof Kozlowski <krzk@...nel.org>,
Kees Cook <keescook@...omium.org>,
Andi Kleen <ak@...ux.intel.com>,
Geert Uytterhoeven <geert+renesas@...der.be>,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
linux-mips@...r.kernel.org, letux-kernel@...nphoenux.org,
kernel@...a-handheld.com
Subject: Re: [RFC v3 1/9] nvmem: add driver for JZ4780 efuse
Hi Srinivas,
Le lun., févr. 17, 2020 at 11:36, Srinivas Kandagatla
<srinivas.kandagatla@...aro.org> a écrit :
>
>
> On 16/02/2020 19:20, H. Nikolaus Schaller wrote:
>> From: PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>
>>
>> This patch brings support for the JZ4780 efuse. Currently it only
>> exposes
>> a read only access to the entire 8K bits efuse memory and nvmem
>> cells.
>>
>> Tested-by: Mathieu Malaterre <malat@...ian.org>
>> Signed-off-by: PrasannaKumar Muralidharan
>> <prasannatsmkumar@...il.com>
>> Signed-off-by: Mathieu Malaterre <malat@...ian.org>
>> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
>> (Signed-off-by: Paul Cercueil <paul@...pouillou.net>)
>> ---
>> drivers/nvmem/Kconfig | 10 ++
>> drivers/nvmem/Makefile | 2 +
>> drivers/nvmem/jz4780-efuse.c | 249
>> +++++++++++++++++++++++++++++++++++
>> 3 files changed, 261 insertions(+)
>> create mode 100644 drivers/nvmem/jz4780-efuse.c
>>
>
> This patch along with 2/9 should be merged into single patch.
> Also please make sure you run checkpatch.pl before sending!
>
>> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
>> index 35efab1ba8d9..10f8e08f5e31 100644
>> --- a/drivers/nvmem/Kconfig
>> +++ b/drivers/nvmem/Kconfig
>> @@ -55,6 +55,16 @@ config NVMEM_IMX_OCOTP_SCU
>> This is a driver for the SCU On-Chip OTP Controller (OCOTP)
>> available on i.MX8 SoCs.
>> +config JZ4780_EFUSE
>> + tristate "JZ4780 EFUSE Memory Support"
>> + depends on MACH_JZ4780 || COMPILE_TEST
>
> what is that this driver depends on MACH_JZ4780 board?
>
>
>> + depends on HAS_IOMEM
>> + help
>> + Say Y here to include support for JZ4780 efuse memory found on
>> + all JZ4780 SoC based devices.
>> + To compile this driver as a module, choose M here: the module
>> + will be called nvmem_jz4780_efuse.
>> +
>> 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 6b466cd1427b..65a268d17807 100644
>> --- a/drivers/nvmem/Makefile
>> +++ b/drivers/nvmem/Makefile
>> @@ -18,6 +18,8 @@ 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-$(CONFIG_JZ4780_EFUSE) += nvmem_jz4780_efuse.o
>> +nvmem_jz4780_efuse-y := jz4780-efuse.o
>> obj-$(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/jz4780-efuse.c
>> b/drivers/nvmem/jz4780-efuse.c
>> new file mode 100644
>> index 000000000000..ac03e1900ef9
>> --- /dev/null
>> +++ b/drivers/nvmem/jz4780-efuse.c
>> @@ -0,0 +1,249 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * JZ4780 EFUSE Memory Support driver
>> + *
>> + * Copyright (c) 2017 PrasannaKumar Muralidharan
>> <prasannatsmkumar@...il.com>
>> + * Copyright (c) 2020 H. Nikolaus Schaller <hns@...delico.com>
>> + */
>> +
>> +/*
>> + * Currently supports JZ4780 efuse which has 8K programmable bit.
>> + * Efuse is separated into seven segments as below:
>> + *
>> + *
>> -----------------------------------------------------------------------
>> + * | 64 bit | 128 bit | 128 bit | 3520 bit | 8 bit | 2296 bit |
>> 2048 bit |
>> + *
>> -----------------------------------------------------------------------
>> + *
>> + * The rom itself is accessed using a 9 bit address line and an 8
>> word wide bus
>> + * which reads/writes based on strobes. The strobe is configured in
>> the config
>> + * register and is based on number of cycles of the bus clock.
>> + *
>> + * Driver supports read only as the writes are done in the Factory.
>> + */
>> +
>> +#include <linux/bitops.h>
>> +#include <linux/clk.h>
>> +#include <linux/module.h>
>> +#include <linux/nvmem-provider.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>
>
>> +#include <linux/regmap.h>
>> +#include <linux/timer.h>
> ?? why do we need these two headers in this patch
>
>
>> +
>> +#define JZ_EFUCTRL (0x0) /* Control Register */
>> +#define JZ_EFUCFG (0x4) /* Configure Register*/
>> +#define JZ_EFUSTATE (0x8) /* Status Register */
>> +#define JZ_EFUDATA(n) (0xC + (n)*4)
>> +
>> +#define JZ_EFUSE_START_ADDR 0x200
>> +
>> +#define JZ_EFUSE_EFUCTRL_CS BIT(30)
>> +#define JZ_EFUSE_EFUCTRL_ADDR_MASK 0x1FF
>> +#define JZ_EFUSE_EFUCTRL_ADDR_SHIFT 21
>> +#define JZ_EFUSE_EFUCTRL_LEN_MASK 0x1F
>> +#define JZ_EFUSE_EFUCTRL_LEN_SHIFT 16
>> +#define JZ_EFUSE_EFUCTRL_PG_EN BIT(15)
>> +#define JZ_EFUSE_EFUCTRL_WR_EN BIT(1)
>> +#define JZ_EFUSE_EFUCTRL_RD_EN BIT(0)
>> +
>> +#define JZ_EFUSE_EFUCFG_INT_EN BIT(31)
>> +#define JZ_EFUSE_EFUCFG_RD_ADJ_MASK 0xF
>
> consider using GENMASK for these masks here.
>
>> +#define JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT 20
>> +#define JZ_EFUSE_EFUCFG_RD_STR_MASK 0xF
>> +#define JZ_EFUSE_EFUCFG_RD_STR_SHIFT 16
>> +#define JZ_EFUSE_EFUCFG_WR_ADJ_MASK 0xF
>> +#define JZ_EFUSE_EFUCFG_WR_ADJ_SHIFT 12
>> +#define JZ_EFUSE_EFUCFG_WR_STR_MASK 0xFFF
>> +#define JZ_EFUSE_EFUCFG_WR_STR_SHIFT 0
>> +
>> +#define JZ_EFUSE_EFUSTATE_WR_DONE BIT(1)
>> +#define JZ_EFUSE_EFUSTATE_RD_DONE BIT(0)
>> +
>> +struct jz4780_efuse {
>> + struct device *dev;
>> + void __iomem *iomem;
>> + struct clk *clk;
>> + unsigned int rd_adj;
>> + unsigned int rd_strobe;
>> +};
>> +
>> +/* We read 32 byte chunks to avoid complexity in the driver. */
>> +static int jz4780_efuse_read_32bytes(struct jz4780_efuse *efuse,
>> char *buf,
>> + unsigned int addr)
>> +{
>> + unsigned int tmp = 0;
>> + int i = 0;
>
> unnecessary initialization of both variables.
>
>> + int timeout = 1000;
>> + int size = 32;
>
> better to #define this STRIDE/CHUNK size. this driver seems to use
> this value in multiple places.
>
>> +
>> + /* 1. Set config register */
>> + tmp = readl(efuse->iomem + JZ_EFUCFG);
>> + tmp &= ~((JZ_EFUSE_EFUCFG_RD_ADJ_MASK <<
>> JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
>> + | (JZ_EFUSE_EFUCFG_RD_STR_MASK << JZ_EFUSE_EFUCFG_RD_STR_SHIFT));
>> + tmp |= (efuse->rd_adj << JZ_EFUSE_EFUCFG_RD_ADJ_SHIFT)
>> + | (efuse->rd_strobe << JZ_EFUSE_EFUCFG_RD_STR_SHIFT);
>
> very odd indenting.
>
>> + writel(tmp, efuse->iomem + JZ_EFUCFG);
>> +
>> + /*
>> + * 2. Set control register to indicate what to read data address,
>> + * read data numbers and read enable.
>> + */
>> + tmp = readl(efuse->iomem + JZ_EFUCTRL);
>> + tmp &= ~(JZ_EFUSE_EFUCFG_RD_STR_SHIFT
>> + | (JZ_EFUSE_EFUCTRL_ADDR_MASK << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
>> + | JZ_EFUSE_EFUCTRL_PG_EN | JZ_EFUSE_EFUCTRL_WR_EN
>> + | JZ_EFUSE_EFUCTRL_WR_EN);
>> +
>> + /* Need to select CS bit if address accesses upper 4Kbits memory */
>> + if (addr >= (JZ_EFUSE_START_ADDR + 512))
>> + tmp |= JZ_EFUSE_EFUCTRL_CS;
>> +
>> + tmp |= (addr << JZ_EFUSE_EFUCTRL_ADDR_SHIFT)
>> + | ((size - 1) << JZ_EFUSE_EFUCTRL_LEN_SHIFT)
>> + | JZ_EFUSE_EFUCTRL_RD_EN;
>> + writel(tmp, efuse->iomem + JZ_EFUCTRL);
>> +
>> + /*
>> + * 3. Wait status register RD_DONE set to 1 or EFUSE interrupted,
>> + * software can read EFUSE data buffer 0 - 8 registers.
>> + */
>> + do {
>> + tmp = readl(efuse->iomem + JZ_EFUSTATE);
>> + usleep_range(1000, 2000);
>> + if (timeout--)
>> + break;
>> + } while (!(tmp & JZ_EFUSE_EFUSTATE_RD_DONE));
>> +
>> + if (timeout <= 0) {
>> + dev_err(efuse->dev, "Timed out while reading\n");
>> + return -EAGAIN;
>> + }
>> +
>> + for (i = 0; i < (size / 4); i++)
>> + *((unsigned int *)(buf + i * 4))
>
> make "unsigned int *buf32" a local variable and use it here, makes it
> much readable code.
>
>> + = readl(efuse->iomem + JZ_EFUDATA(i));
>> +
>> + return 0;
>> +}
>> +
>> +/* main entry point */
>> +static int jz4780_efuse_read(void *context, unsigned int offset,
>> + void *val, size_t bytes)
>> +{
>> + struct jz4780_efuse *efuse = context;
>> + int ret;
>> +
>> + while (bytes > 0) {
>> + unsigned int start = offset & ~(32 - 1);
>> + unsigned chunk = min(bytes, (start + 32 - offset));
>> +
>> + if (start == offset && chunk == 32) {
>> + ret = jz4780_efuse_read_32bytes(efuse, val, start);
>> + if (ret < 0)
>> + return ret;
>> +
>> + } else {
>> + char buf[32];
>> + ret = jz4780_efuse_read_32bytes(efuse, buf, start);
>> + if (ret < 0)
>> + return ret;
>> +
>> + memcpy(val, &buf[offset - start], chunk);
>> + }
>> +
>> + val += chunk;
>> + offset += chunk;
>> + bytes -= chunk;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static struct nvmem_config jz4780_efuse_nvmem_config = {
>> + .name = "jz4780-efuse",
>> + .read_only = true,
>
> this value comes from device tree bindings, do we still need to
> specify this here?
I think its semantic is different - devicetree specifies that you want
the nvmem to be readonly, this one specifies that the driver cannot do
read-write anyway.
With that said, there is no .reg_write, so .read_only will be enforced
to 'true' anyway, so it can be removed.
-Paul
>
>> + .size = 1024,
>> + .word_size = 1,
>> + .stride = 1,
>> + .owner = THIS_MODULE,
>> + .reg_read = jz4780_efuse_read,
>> +};
>> +
>> +static int jz4780_efuse_probe(struct platform_device *pdev)
>> +{
>> + struct nvmem_device *nvmem;
>> + struct jz4780_efuse *efuse;
>> + struct resource *res;
>> + unsigned long clk_rate;
>> + struct device *dev = &pdev->dev;
>> +
>> + efuse = devm_kzalloc(&pdev->dev, sizeof(*efuse), GFP_KERNEL);
>> + if (!efuse)
>> + return -ENOMEM;
>> +
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> + efuse->iomem = devm_ioremap(&pdev->dev, res->start,
>> resource_size(res));
>> + if (IS_ERR(efuse->iomem))
>> + return PTR_ERR(efuse->iomem);
>> +
>> + efuse->clk = devm_clk_get(&pdev->dev, "bus_clk");
>> + if (IS_ERR(efuse->clk))
>> + return PTR_ERR(efuse->clk);
>
> Who is enabling this clk?
>
>
>> +
>> + clk_rate = clk_get_rate(efuse->clk);
>> + /*
>> + * rd_adj and rd_strobe are 4 bit values
>> + * bus clk period * (rd_adj + 1) > 6.5ns
>> + * bus clk period * (rd_adj + 5 + rd_strobe) > 35ns
>> + */
>> + efuse->rd_adj = (((6500 * (clk_rate / 1000000)) / 1000000) + 1) -
>> 1;
>> + efuse->rd_strobe = ((((35000 * (clk_rate / 1000000)) / 1000000) +
>> 1)
>> + - 5 - efuse->rd_adj);
>> +
>> + if ((efuse->rd_adj > 0x1F) || (efuse->rd_strobe > 0x1F)) {
>> + dev_err(&pdev->dev, "Cannot set clock configuration\n");
>> + return -EINVAL;
>> + }
>> + efuse->dev = dev;
>> +
>> + jz4780_efuse_nvmem_config.dev = &pdev->dev;
>> + jz4780_efuse_nvmem_config.priv = efuse;
>> +
>> + nvmem = nvmem_register(&jz4780_efuse_nvmem_config);
>
> devm variant here?
>
>
>> + if (IS_ERR(nvmem))
>> + return PTR_ERR(nvmem);
>> +
>> + platform_set_drvdata(pdev, nvmem);
>> +
>> + return 0;
>> +}
>> +
>> +static int jz4780_efuse_remove(struct platform_device *pdev)
>> +{
>> + struct nvmem_device *nvmem = platform_get_drvdata(pdev);
>> +
>> + nvmem_unregister(nvmem);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id jz4780_efuse_match[] = {
>> + { .compatible = "ingenic,jz4780-efuse" },
>> + { /* sentinel */ },
>> +};
>> +MODULE_DEVICE_TABLE(of, jz4780_efuse_match);
>> +
>> +static struct platform_driver jz4780_efuse_driver = {
>> + .probe = jz4780_efuse_probe,
>> + .remove = jz4780_efuse_remove,
>> + .driver = {
>> + .name = "jz4780-efuse",
>> + .of_match_table = jz4780_efuse_match,
>> + },
>> +};
>> +module_platform_driver(jz4780_efuse_driver);
>> +
>> +MODULE_AUTHOR("PrasannaKumar Muralidharan
>> <prasannatsmkumar@...il.com>");
>> +MODULE_AUTHOR("H. Nikolaus Schaller <hns@...delico.com>");
>> +MODULE_DESCRIPTION("Ingenic JZ4780 efuse driver");
>> +MODULE_LICENSE("GPL v2");
>>
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