nvmem: imx: add i.MX8 nvmem driver

This patch adds i.MX8 nvmem ocotp driver to access fuse via
RPC to i.MX8 system controller.

Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/Kconfig

@@ -47,6 +47,13 @@ config NVMEM_IMX_OCOTP
 	  This driver can also be built as a module. If so, the module
 	  will be called nvmem-imx-ocotp.
 
+config NVMEM_IMX_OCOTP_SCU
+	tristate "i.MX8 SCU On-Chip OTP Controller support"
+	depends on IMX_SCU
+	help
+	  This is a driver for the SCU On-Chip OTP Controller (OCOTP)
+	  available on i.MX8 SoCs.
+
 config NVMEM_LPC18XX_EEPROM
 	tristate "NXP LPC18XX EEPROM Memory Support"
 	depends on ARCH_LPC18XX || COMPILE_TEST

drivers/nvmem/Makefile

@@ -16,6 +16,8 @@ obj-$(CONFIG_NVMEM_IMX_IIM)	+= nvmem-imx-iim.o
 nvmem-imx-iim-y			:= imx-iim.o
 obj-$(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_NVMEM_LPC18XX_EEPROM)	+= nvmem_lpc18xx_eeprom.o
 nvmem_lpc18xx_eeprom-y	:= lpc18xx_eeprom.o
 obj-$(CONFIG_NVMEM_LPC18XX_OTP)	+= nvmem_lpc18xx_otp.o

drivers/nvmem/imx-ocotp-scu.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * i.MX8 OCOTP fusebox driver
+ *
+ * Copyright 2019 NXP
+ *
+ * Peng Fan <peng.fan@nxp.com>
+ */
+
+#include <linux/firmware/imx/sci.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+enum ocotp_devtype {
+	IMX8QXP,
+};
+
+struct ocotp_devtype_data {
+	int devtype;
+	int nregs;
+};
+
+struct ocotp_priv {
+	struct device *dev;
+	const struct ocotp_devtype_data *data;
+	struct imx_sc_ipc *nvmem_ipc;
+};
+
+struct imx_sc_msg_misc_fuse_read {
+	struct imx_sc_rpc_msg hdr;
+	u32 word;
+} __packed;
+
+static struct ocotp_devtype_data imx8qxp_data = {
+	.devtype = IMX8QXP,
+	.nregs = 800,
+};
+
+static int imx_sc_misc_otp_fuse_read(struct imx_sc_ipc *ipc, u32 word,
+				     u32 *val)
+{
+	struct imx_sc_msg_misc_fuse_read msg;
+	struct imx_sc_rpc_msg *hdr = &msg.hdr;
+	int ret;
+
+	hdr->ver = IMX_SC_RPC_VERSION;
+	hdr->svc = IMX_SC_RPC_SVC_MISC;
+	hdr->func = IMX_SC_MISC_FUNC_OTP_FUSE_READ;
+	hdr->size = 2;
+
+	msg.word = word;
+
+	ret = imx_scu_call_rpc(ipc, &msg, true);
+	if (ret)
+		return ret;
+
+	*val = msg.word;
+
+	return 0;
+}
+
+static int imx_scu_ocotp_read(void *context, unsigned int offset,
+			      void *val, size_t bytes)
+{
+	struct ocotp_priv *priv = context;
+	u32 count, index, num_bytes;
+	u32 *buf;
+	void *p;
+	int i, ret;
+
+	index = offset >> 2;
+	num_bytes = round_up((offset % 4) + bytes, 4);
+	count = num_bytes >> 2;
+
+	if (count > (priv->data->nregs - index))
+		count = priv->data->nregs - index;
+
+	p = kzalloc(num_bytes, GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+
+	buf = p;
+
+	for (i = index; i < (index + count); i++) {
+		if (priv->data->devtype == IMX8QXP) {
+			if ((i > 271) && (i < 544)) {
+				*buf++ = 0;
+				continue;
+			}
+		}
+
+		ret = imx_sc_misc_otp_fuse_read(priv->nvmem_ipc, i, buf);
+		if (ret) {
+			kfree(p);
+			return ret;
+		}
+		buf++;
+	}
+
+	memcpy(val, (u8 *)p + offset % 4, bytes);
+
+	kfree(p);
+
+	return 0;
+}
+
+static struct nvmem_config imx_scu_ocotp_nvmem_config = {
+	.name = "imx-scu-ocotp",
+	.read_only = true,
+	.word_size = 4,
+	.stride = 1,
+	.owner = THIS_MODULE,
+	.reg_read = imx_scu_ocotp_read,
+};
+
+static const struct of_device_id imx_scu_ocotp_dt_ids[] = {
+	{ .compatible = "fsl,imx8qxp-scu-ocotp", (void *)&imx8qxp_data },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, imx_scu_ocotp_dt_ids);
+
+static int imx_scu_ocotp_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ocotp_priv *priv;
+	struct nvmem_device *nvmem;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	ret = imx_scu_get_handle(&priv->nvmem_ipc);
+	if (ret)
+		return ret;
+
+	priv->data = of_device_get_match_data(dev);
+	priv->dev = dev;
+	imx_scu_ocotp_nvmem_config.size = 4 * priv->data->nregs;
+	imx_scu_ocotp_nvmem_config.dev = dev;
+	imx_scu_ocotp_nvmem_config.priv = priv;
+	nvmem = devm_nvmem_register(dev, &imx_scu_ocotp_nvmem_config);
+
+	return PTR_ERR_OR_ZERO(nvmem);
+}
+
+static struct platform_driver imx_scu_ocotp_driver = {
+	.probe	= imx_scu_ocotp_probe,
+	.driver = {
+		.name	= "imx_scu_ocotp",
+		.of_match_table = imx_scu_ocotp_dt_ids,
+	},
+};
+module_platform_driver(imx_scu_ocotp_driver);
+
+MODULE_AUTHOR("Peng Fan <peng.fan@nxp.com>");
+MODULE_DESCRIPTION("i.MX8 SCU OCOTP fuse box driver");
+MODULE_LICENSE("GPL v2");