[v2,1/4] Add eSPI device driver (flash channel)

diff --git a/drivers/soc/aspeed/Kconfig b/drivers/soc/aspeed/Kconfig
index f579ee0b5afa..c300ee8fe33a 100644
--- a/drivers/soc/aspeed/Kconfig
+++ b/drivers/soc/aspeed/Kconfig
@@ -52,6 +52,44 @@  config ASPEED_SOCINFO
 	help
 	  Say yes to support decoding of ASPEED BMC information.
 
+menu "ASPEED eSPI Support"
+
+config ASPEED_ESPI
+	bool "ASPEED eSPI slave driver"
+	select REGMAP
+	select MFD_SYSCON
+	depends on ASPEED_ESPI_FLASH
+	default n
+	help
+	  Enable driver support for the Aspeed eSPI engine. The eSPI engine
+	  plays as a slave device in BMC to communicate with the Host over
+	  the eSPI interface.
+
+menu "ASPEED eSPI Flash channel support"
+
+config  ASPEED_ESPI_FLASH
+	bool "ASPEED eSPI flash channel support"
+	default n
+	depends on ASPEED_ESPI_FLASH_MAFS
+	select ASPEED_ESPI
+	help
+	  Enable eSPI flash channel support.
+
+menu "ASPEED eSPI flash modes"
+
+config ASPEED_ESPI_FLASH_MAFS
+	bool "Master attached flash sharing (MAFS) support in eSPI"
+	default n
+	select ASPEED_ESPI_FLASH
+	help
+	  Select this option if you have a Master attached flash connected to
+	  the eSPI controller.
+
+endmenu # eSPI Flash Modes
+endmenu # eSPI Flash Channel support
+endmenu # eSPI Support
+
+
 endmenu
 
 endif
diff --git a/drivers/soc/aspeed/Makefile b/drivers/soc/aspeed/Makefile
index b35d74592964..cecbba700071 100644
--- a/drivers/soc/aspeed/Makefile
+++ b/drivers/soc/aspeed/Makefile
@@ -4,3 +4,5 @@  obj-$(CONFIG_ASPEED_LPC_SNOOP)		+= aspeed-lpc-snoop.o
 obj-$(CONFIG_ASPEED_UART_ROUTING)	+= aspeed-uart-routing.o
 obj-$(CONFIG_ASPEED_P2A_CTRL)		+= aspeed-p2a-ctrl.o
 obj-$(CONFIG_ASPEED_SOCINFO)		+= aspeed-socinfo.o
+obj-$(CONFIG_ASPEED_ESPI)               += aspeed-espi-ctrl.o
+obj-$(CONFIG_ASPEED_ESPI_FLASH_MAFS)    += aspeed-espi-flash-mafs.o
diff --git a/drivers/soc/aspeed/aspeed-espi-ctrl.c b/drivers/soc/aspeed/aspeed-espi-ctrl.c
new file mode 100644
index 000000000000..7e2b86849fd0
--- /dev/null
+++ b/drivers/soc/aspeed/aspeed-espi-ctrl.c
@@ -0,0 +1,197 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2024 Aspeed Technology Inc.
+ */
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/miscdevice.h>
+#include <linux/dma-mapping.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+
+#include "aspeed-espi-ctrl.h"
+#include "aspeed-espi-flash.h"
+
+/**
+ * aspeed_espi_ctrl_isr - function to handle various interrupts
+ * @irq: interrupt line
+ * @arg: pointer to access device registers
+ *
+ * Returns IRQ_HANDLED
+ */
+static irqreturn_t aspeed_espi_ctrl_isr(int irq, void *arg)
+{
+	uint32_t sts;
+	struct aspeed_espi_ctrl *espi_ctrl = (struct aspeed_espi_ctrl *)arg;
+
+	regmap_read(espi_ctrl->map, ESPI_INT_STS, &sts);
+
+	if (sts & ESPI_INT_STS_FLASH_BITS) {
+		aspeed_espi_flash_event(sts, espi_ctrl->flash);
+		regmap_write(espi_ctrl->map, ESPI_INT_STS,
+			     sts & ESPI_INT_STS_FLASH_BITS);
+	}
+
+	if (sts & ESPI_INT_STS_HW_RST_DEASSERT) {
+		aspeed_espi_flash_enable(espi_ctrl->flash);
+
+		regmap_write(espi_ctrl->map, ESPI_SYSEVT_INT_T0, 0x0);
+		regmap_write(espi_ctrl->map, ESPI_SYSEVT_INT_T1, 0x0);
+		regmap_write(espi_ctrl->map, ESPI_SYSEVT_INT_EN, 0xffffffff);
+
+		regmap_write(espi_ctrl->map, ESPI_SYSEVT1_INT_T0, 0x1);
+		regmap_write(espi_ctrl->map, ESPI_SYSEVT1_INT_EN, 0x1);
+
+		regmap_update_bits(espi_ctrl->map, ESPI_INT_EN,
+				   ESPI_INT_EN_HW_RST_DEASSERT,
+				   ESPI_INT_EN_HW_RST_DEASSERT);
+
+		regmap_update_bits(
+			espi_ctrl->map, ESPI_SYSEVT,
+			ESPI_SYSEVT_SLV_BOOT_STS | ESPI_SYSEVT_SLV_BOOT_DONE,
+			ESPI_SYSEVT_SLV_BOOT_STS | ESPI_SYSEVT_SLV_BOOT_DONE);
+
+		regmap_write(espi_ctrl->map, ESPI_INT_STS,
+			     ESPI_INT_STS_HW_RST_DEASSERT);
+	}
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * aspeed_espi_ctrl_probe - function to probe the platform driver
+ * @pdev: platform device
+ *
+ * Returns 0 on success, -ENOMEM on error
+ */
+static int aspeed_espi_ctrl_probe(struct platform_device *pdev)
+{
+	int rc = 0;
+	struct aspeed_espi_ctrl *espi_ctrl;
+	struct device *dev = &pdev->dev;
+
+	espi_ctrl = devm_kzalloc(dev, sizeof(*espi_ctrl), GFP_KERNEL);
+	if (!espi_ctrl)
+		return -ENOMEM;
+
+	espi_ctrl->model = of_device_get_match_data(dev);
+
+	espi_ctrl->map = syscon_node_to_regmap(dev->parent->of_node);
+	if (IS_ERR(espi_ctrl->map)) {
+		dev_err(dev, "cannot get remap\n");
+		return PTR_ERR(espi_ctrl->map);
+	}
+
+	espi_ctrl->irq = platform_get_irq(pdev, 0);
+	if (espi_ctrl->irq < 0)
+		return espi_ctrl->irq;
+
+	espi_ctrl->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(espi_ctrl->clk)) {
+		dev_err(dev, "cannot get clock\n");
+		return PTR_ERR(espi_ctrl->clk);
+	}
+
+	rc = clk_prepare_enable(espi_ctrl->clk);
+	if (rc) {
+		dev_err(dev, "cannot enable clock\n");
+		return rc;
+	}
+
+	/*
+	 * This takes care of deferred probe , incase the mtd core
+	 * subsystem is not probed yet.
+	 */
+	espi_ctrl->flash = aspeed_espi_flash_alloc(dev, espi_ctrl);
+	if (IS_ERR(espi_ctrl->flash)) {
+		dev_err(dev, "failed to allocate flash channel\n");
+		pr_info("flash alloc failed with return code %ld\n",
+			PTR_ERR(espi_ctrl->flash));
+		return PTR_ERR(espi_ctrl->flash);
+	}
+
+	regmap_write(espi_ctrl->map, ESPI_SYSEVT_INT_T0, 0x0);
+	regmap_write(espi_ctrl->map, ESPI_SYSEVT_INT_T1, 0x0);
+	regmap_write(espi_ctrl->map, ESPI_SYSEVT_INT_EN, 0xffffffff);
+
+	regmap_write(espi_ctrl->map, ESPI_SYSEVT1_INT_T0, 0x1);
+	regmap_write(espi_ctrl->map, ESPI_SYSEVT1_INT_EN, 0x1);
+
+	rc = devm_request_irq(dev, espi_ctrl->irq, aspeed_espi_ctrl_isr, 0,
+			      DEVICE_NAME, espi_ctrl);
+	if (rc) {
+		dev_err(dev, "failed to request IRQ\n");
+		return rc;
+	}
+
+	// clear the interrupt enable register
+	regmap_write(espi_ctrl->map, ESPI_INT_EN_CLR, 0x7fffffff);
+
+	// Disable the interrupts in all channels except flash channel
+	regmap_update_bits(espi_ctrl->map, ESPI_INT_EN,
+			   ESPI_INT_EN_FLASH_BITS | ESPI_INT_EN_HW_RST_DEASSERT,
+			   ESPI_INT_EN_FLASH_BITS |
+				   ESPI_INT_STS_HW_RST_DEASSERT);
+
+	dev_set_drvdata(dev, espi_ctrl);
+
+	dev_info(dev, "module loaded\n");
+
+	return 0;
+}
+
+/**
+ * aspeed_espi_ctrl_remove - Release the driver
+ * @pdev: the platform device
+ *
+ * Returns 0
+ */
+static int aspeed_espi_ctrl_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct aspeed_espi_ctrl *espi_ctrl = dev_get_drvdata(dev);
+
+	aspeed_espi_flash_free(dev, espi_ctrl->flash);
+
+	return 0;
+}
+
+static const struct aspeed_espi_model ast2500_model = {
+	.version = ESPI_AST2500,
+};
+
+static const struct aspeed_espi_model ast2600_model = {
+	.version = ESPI_AST2600,
+};
+
+static const struct of_device_id aspeed_espi_ctrl_of_matches[] = {
+	{ .compatible = "aspeed,ast2500-espi-ctrl", .data = &ast2500_model },
+	{ .compatible = "aspeed,ast2600-espi-ctrl", .data = &ast2600_model },
+	{},
+};
+MODULE_DEVICE_TABLE(of, aspeed_espi_ctrl_of_matches);
+
+static struct platform_driver aspeed_espi_ctrl_driver = {
+	.driver = {
+		.name = DEVICE_NAME,
+		.of_match_table = aspeed_espi_ctrl_of_matches,
+	},
+	.probe = aspeed_espi_ctrl_probe,
+	.remove = aspeed_espi_ctrl_remove,
+};
+
+module_platform_driver(aspeed_espi_ctrl_driver);
+
+MODULE_AUTHOR("Manojkiran Eda <manojkiran.eda@gmail.com>");
+MODULE_AUTHOR("Patrick Rudolph <patrick.rudolph@9elements.com>");
+MODULE_AUTHOR("Chia-Wei Wang <chiawei_wang@aspeedtech.com>");
+MODULE_AUTHOR("Ryan Chen <ryan_chen@aspeedtech.com>");
+MODULE_DESCRIPTION("Control of Aspeed eSPI Slave Device");
+MODULE_LICENSE("GPL");
diff --git a/drivers/soc/aspeed/aspeed-espi-ctrl.h b/drivers/soc/aspeed/aspeed-espi-ctrl.h
new file mode 100644
index 000000000000..5c4950c84b01
--- /dev/null
+++ b/drivers/soc/aspeed/aspeed-espi-ctrl.h
@@ -0,0 +1,169 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2024 Aspeed Technology Inc.
+ */
+#ifndef _ASPEED_ESPI_CTRL_H_
+#define _ASPEED_ESPI_CTRL_H_
+
+#include <linux/bits.h>
+
+#define DEVICE_NAME "aspeed-espi-ctrl"
+
+/**
+ * enum aspeed_espi_version - Enumeration to capture aspeed versions that this
+ *                            driver supports
+ * @ESPI_AST2500: eSPI for AST2500 Model
+ * @ESPI_AST2600: eSPI for AST2600 Model
+ *
+ * This enumeration captures various aspeed models that this driver supports
+ */
+
+enum aspeed_espi_version {
+	ESPI_AST2500,
+	ESPI_AST2600,
+};
+
+/**
+ * struct aspeed_espi_model - structure to capture version of espi
+ * @version: espi version
+ *
+ * Structure to capture version of eSPI
+ */
+struct aspeed_espi_model {
+	uint32_t version;
+};
+
+/**
+ * struct aspeed_espi_ctrl - structure to group various channels of the driver
+ * @dev: platform device pointer
+ * @map: register map for the device
+ * @clk: clock for the device
+ * @irq: interrupt request
+ * @flash: pointer to flash channel of eSPI
+ * @model: pointer to version of eSPI
+ *
+ * Structure to capture version of eSPI
+ */
+struct aspeed_espi_ctrl {
+	struct device *dev;
+	struct regmap *map;
+	struct clk *clk;
+	int irq;
+	struct aspeed_espi_flash *flash;
+	const struct aspeed_espi_model *model;
+};
+
+/* eSPI register offset */
+#define ESPI_CTRL 0x000
+#define ESPI_CTRL_FLASH_TX_DMA_EN BIT(23)
+#define ESPI_CTRL_FLASH_RX_DMA_EN BIT(22)
+#define ESPI_CTRL_FLASH_SW_MODE_MASK GENMASK(11, 10)
+#define ESPI_CTRL_FLASH_SW_MODE_SHIFT 10
+#define ESPI_CTRL_FLASH_SW_RDY BIT(7)
+
+#define ESPI_STS 0x004
+#define ESPI_CTRL_FLASH_CHAN_RDY BIT(6)
+
+#define ESPI_INT_STS 0x008
+#define ESPI_INT_STS_HW_RST_DEASSERT BIT(31)
+#define ESPI_INT_STS_FLASH_TX_ERR BIT(21)
+#define ESPI_INT_STS_FLASH_TX_ABT BIT(19)
+#define ESPI_INT_STS_FLASH_RX_ABT BIT(15)
+#define ESPI_INT_STS_FLASH_TX_CMPLT BIT(7)
+#define ESPI_INT_STS_FLASH_RX_CMPLT BIT(6)
+#define ESPI_INT_EN 0x00c
+#define ESPI_INT_EN_HW_RST_DEASSERT BIT(31)
+#define ESPI_INT_EN_FLASH_TX_ERR BIT(21)
+#define ESPI_INT_EN_FLASH_TX_ABT BIT(19)
+#define ESPI_INT_EN_FLASH_RX_ABT BIT(15)
+#define ESPI_INT_EN_FLASH_TX_CMPLT BIT(7)
+#define ESPI_INT_EN_FLASH_RX_CMPLT BIT(6)
+#define ESPI_INT_EN_CLR 0x0fc
+#define ESPI_FLASH_RX_DMA 0x060
+#define ESPI_FLASH_RX_CTRL 0x064
+#define ESPI_FLASH_RX_CTRL_PEND_SERV BIT(31)
+#define ESPI_FLASH_RX_CTRL_LEN_MASK GENMASK(23, 12)
+#define ESPI_FLASH_RX_CTRL_LEN_SHIFT 12
+#define ESPI_FLASH_RX_CTRL_TAG_MASK GENMASK(11, 8)
+#define ESPI_FLASH_RX_CTRL_TAG_SHIFT 8
+#define ESPI_FLASH_RX_CTRL_CYC_MASK GENMASK(7, 0)
+#define ESPI_FLASH_RX_CTRL_CYC_SHIFT 0
+#define ESPI_FLASH_RX_PORT 0x068
+#define ESPI_FLASH_TX_DMA 0x070
+#define ESPI_FLASH_TX_CTRL 0x074
+#define ESPI_FLASH_TX_CTRL_TRIGGER BIT(31)
+#define ESPI_FLASH_TX_CTRL_LEN_MASK GENMASK(23, 12)
+#define ESPI_FLASH_TX_CTRL_LEN_SHIFT 12
+#define ESPI_FLASH_TX_CTRL_TAG_MASK GENMASK(11, 8)
+#define ESPI_FLASH_TX_CTRL_TAG_SHIFT 8
+#define ESPI_FLASH_TX_CTRL_CYC_MASK GENMASK(7, 0)
+#define ESPI_FLASH_TX_CTRL_CYC_SHIFT 0
+#define ESPI_FLASH_TX_PORT 0x078
+#define ESPI_CTRL2 0x080
+#define ESPI_CTRL2_MEMCYC_RD_DIS BIT(6)
+#define ESPI_CTRL2_MEMCYC_WR_DIS BIT(4)
+#define ESPI_SYSEVT_INT_EN 0x094
+#define ESPI_SYSEVT 0x098
+#define ESPI_SYSEVT_HOST_RST_ACK BIT(27)
+#define ESPI_SYSEVT_RST_CPU_INIT BIT(26)
+#define ESPI_SYSEVT_SLV_BOOT_STS BIT(23)
+#define ESPI_SYSEVT_NON_FATAL_ERR BIT(22)
+#define ESPI_SYSEVT_FATAL_ERR BIT(21)
+#define ESPI_SYSEVT_SLV_BOOT_DONE BIT(20)
+#define ESPI_SYSEVT_NMI_OUT BIT(10)
+#define ESPI_SYSEVT_SMI_OUT BIT(9)
+#define ESPI_SYSEVT_HOST_RST_WARN BIT(8)
+#define ESPI_SYSEVT_PLTRSTN BIT(5)
+#define ESPI_SYSEVT_SUSPEND BIT(4)
+#define ESPI_SYSEVT_S5_SLEEP BIT(2)
+#define ESPI_SYSEVT_S4_SLEEP BIT(1)
+#define ESPI_SYSEVT_S3_SLEEP BIT(0)
+#define ESPI_GEN_CAP_N_CONF 0x0a0
+#define ESPI_CH0_CAP_N_CONF 0x0a4
+#define ESPI_CH1_CAP_N_CONF 0x0a8
+#define ESPI_CH2_CAP_N_CONF 0x0ac
+#define ESPI_CH3_CAP_N_CONF 0x0b0
+#define ESPI_CH3_CAP_N_CONF_ERASE_MASK GENMASK(4, 2)
+#define ESPI_CH3_CAP_N_CONF_ERASE_SHIFT 2
+#define ESPI_CH3_CAP_N_CONF_ERASE_SIZE_4KB 1
+#define ESPI_CH3_CAP_N_CONF_ERASE_SIZE_64KB 2
+#define ESPI_CH3_CAP_N_CONF_ERASE_SIZE_4KB_64KB 3
+#define ESPI_CH3_CAP_N_CONF_ERASE_SIZE_128KB 4
+#define ESPI_CH3_CAP_N_CONF_ERASE_SIZE_256KB 5
+#define ESPI_CH3_CAP_N_CONF2 0x0b4
+#define ESPI_SYSEVT1_INT_EN 0x100
+#define ESPI_SYSEVT1 0x104
+#define ESPI_SYSEVT1_SUSPEND_ACK BIT(20)
+#define ESPI_SYSEVT1_SUSPEND_WARN BIT(0)
+#define ESPI_SYSEVT_INT_T0 0x110
+#define ESPI_SYSEVT_INT_T1 0x114
+#define ESPI_SYSEVT_INT_T2 0x118
+#define ESPI_SYSEVT_INT_T2_HOST_RST_WARN ESPI_SYSEVT_HOST_RST_WARN
+#define ESPI_SYSEVT_INT_STS 0x11c
+#define ESPI_SYSEVT_INT_STS_NMI_OUT ESPI_SYSEVT_NMI_OUT
+#define ESPI_SYSEVT_INT_STS_SMI_OUT ESPI_SYSEVT_SMI_OUT
+#define ESPI_SYSEVT_INT_STS_HOST_RST_WARN ESPI_SYSEVT_HOST_RST_WARN
+#define ESPI_SYSEVT_INT_STS_PLTRSTN ESPI_SYSEVT_PLTRSTN
+#define ESPI_SYSEVT_INT_STS_SUSPEND ESPI_SYSEVT_SUSPEND
+#define ESPI_SYSEVT_INT_STS_S5_SLEEP ESPI_SYSEVT_INT_S5_SLEEP
+#define ESPI_SYSEVT_INT_STS_S4_SLEEP ESPI_SYSEVT_INT_S4_SLEEP
+#define ESPI_SYSEVT_INT_STS_S3_SLEEP ESPI_SYSEVT_INT_S3_SLEEP
+#define ESPI_SYSEVT1_INT_T0 0x120
+#define ESPI_SYSEVT1_INT_T1 0x124
+#define ESPI_SYSEVT1_INT_T2 0x128
+#define ESPI_SYSEVT1_INT_STS 0x12c
+#define ESPI_SYSEVT1_INT_STS_SUSPEND_WARN ESPI_SYSEVT1_SUSPEND_WARN
+
+/* collect ESPI_INT_STS bits of eSPI channels for convenience */
+#define ESPI_INT_STS_FLASH_BITS                                    \
+	(ESPI_INT_STS_FLASH_TX_ERR | ESPI_INT_STS_FLASH_TX_ABT |   \
+	 ESPI_INT_STS_FLASH_RX_ABT | ESPI_INT_STS_FLASH_TX_CMPLT | \
+	 ESPI_INT_STS_FLASH_RX_CMPLT)
+
+/* collect ESPI_INT_EN bits of eSPI channels for convenience */
+#define ESPI_INT_EN_FLASH_BITS                                   \
+	(ESPI_INT_EN_FLASH_TX_ERR | ESPI_INT_EN_FLASH_TX_ABT |   \
+	 ESPI_INT_EN_FLASH_RX_ABT | ESPI_INT_EN_FLASH_TX_CMPLT | \
+	 ESPI_INT_EN_FLASH_RX_CMPLT)
+
+#endif
diff --git a/drivers/soc/aspeed/aspeed-espi-flash-mafs.c b/drivers/soc/aspeed/aspeed-espi-flash-mafs.c
new file mode 100644
index 000000000000..ac5d55833109
--- /dev/null
+++ b/drivers/soc/aspeed/aspeed-espi-flash-mafs.c
@@ -0,0 +1,467 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyrigt 2024 Aspeed Technology Inc.
+ */
+#include <linux/fs.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+#include <linux/miscdevice.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+#include <linux/miscdevice.h>
+#include <linux/dma-mapping.h>
+
+#include "aspeed-espi-ctrl.h"
+#include "aspeed-espi-flash.h"
+
+static long aspeed_espi_flash_rx(uint8_t *cyc, uint16_t *len, uint32_t *addr,
+				 uint8_t *pkt, size_t *pkt_len,
+				 struct aspeed_espi_flash *espi_flash)
+{
+	unsigned long flags;
+	uint32_t reg, rx_pkt_len, addr_be;
+	struct aspeed_espi_ctrl *espi_ctrl = espi_flash->ctrl;
+	void *rx_virt_ptr;
+	ulong to;
+	int ret;
+
+	spin_lock_irqsave(&espi_flash->spinlock, flags);
+
+	to = msecs_to_jiffies(100);
+	ret = wait_event_interruptible_lock_irq_timeout(
+		espi_flash->wq, espi_flash->rx_sts, espi_flash->spinlock, to);
+
+	spin_unlock_irqrestore(&espi_flash->spinlock, flags);
+
+	if (ret == -ERESTARTSYS)
+		return -EINTR;
+	else if (!ret)
+		return -ETIMEDOUT;
+	else if (espi_flash->rx_sts & ESPI_INT_STS_FLASH_RX_ABT)
+		return -EFAULT;
+	else
+		ret = 0;
+
+	/* common header (i.e. cycle type, tag, and length) is taken by HW */
+	regmap_read(espi_ctrl->map, ESPI_FLASH_RX_CTRL, &reg);
+	*cyc = (reg & ESPI_FLASH_RX_CTRL_CYC_MASK) >>
+	       ESPI_FLASH_RX_CTRL_CYC_SHIFT;
+	*len = (reg & ESPI_FLASH_RX_CTRL_LEN_MASK) >>
+	       ESPI_FLASH_RX_CTRL_LEN_SHIFT;
+
+	/*
+	 * calculate the length of the rest part of the
+	 * eSPI packet to be read from HW and copied to
+	 * user space.
+	 */
+	switch (*cyc) {
+	case ESPI_FLASH_READ:
+	case ESPI_FLASH_WRITE:
+	case ESPI_FLASH_ERASE:
+		rx_virt_ptr = espi_flash->dma.rx_virt + sizeof(addr_be);
+		rx_pkt_len = (*len) ? *len : ESPI_PLD_LEN_MAX;
+
+		if (addr) {
+			memcpy(&addr_be, espi_flash->dma.rx_virt,
+			       sizeof(addr_be));
+			*addr = ntohl(addr_be);
+		}
+
+		break;
+	case ESPI_FLASH_SUC_CMPLT_D_MIDDLE:
+	case ESPI_FLASH_SUC_CMPLT_D_FIRST:
+	case ESPI_FLASH_SUC_CMPLT_D_LAST:
+	case ESPI_FLASH_SUC_CMPLT_D_ONLY:
+		rx_pkt_len = (*len) ? *len : ESPI_PLD_LEN_MAX;
+		rx_virt_ptr = espi_flash->dma.rx_virt;
+		break;
+	case ESPI_FLASH_SUC_CMPLT:
+	case ESPI_FLASH_UNSUC_CMPLT:
+	case ESPI_FLASH_UNSUC_CMPLT_ONLY:
+		/* No data received */
+		rx_pkt_len = 0;
+		rx_virt_ptr = NULL;
+		break;
+	default:
+		rx_pkt_len = 0;
+		ret = -EFAULT;
+	}
+	if (pkt_len)
+		*pkt_len = rx_pkt_len;
+
+	if (rx_pkt_len && pkt_len && pkt) {
+		if (*pkt_len >= rx_pkt_len)
+			memcpy(pkt, rx_virt_ptr, rx_pkt_len);
+		else
+			ret = -EINVAL;
+	}
+
+	spin_lock_irqsave(&espi_flash->spinlock, flags);
+
+	regmap_write_bits(espi_ctrl->map, ESPI_FLASH_RX_CTRL,
+			  ESPI_FLASH_RX_CTRL_PEND_SERV,
+			  ESPI_FLASH_RX_CTRL_PEND_SERV);
+
+	espi_flash->rx_sts = 0;
+
+	spin_unlock_irqrestore(&espi_flash->spinlock, flags);
+	return ret;
+}
+
+static long
+aspeed_espi_flash_rx_get_completion(struct aspeed_espi_flash *espi_flash)
+{
+	uint8_t cyc;
+	uint16_t len;
+	int ret;
+
+	ret = aspeed_espi_flash_rx(&cyc, &len, NULL, NULL, 0, espi_flash);
+	if (ret)
+		return ret;
+
+	if (cyc != ESPI_FLASH_SUC_CMPLT) {
+		dev_notice(espi_flash->ctrl->dev, "eSPI Rx response was not successful\n");
+		return -EFAULT;
+	}
+	return 0;
+}
+
+static long aspeed_espi_flash_put_tx(uint8_t cyc, uint16_t len, uint32_t addr,
+				     const uint8_t *pkt, size_t pkt_len,
+				     struct aspeed_espi_flash *espi_flash)
+{
+	struct aspeed_espi_ctrl *espi_ctrl = espi_flash->ctrl;
+	unsigned long flags;
+	uint32_t reg, addr_be;
+	ulong to;
+	int ret = 0;
+
+	/* Test if flash channel is ready */
+	regmap_read(espi_ctrl->map, ESPI_STS, &reg);
+	if (!(reg & ESPI_CTRL_FLASH_CHAN_RDY)) {
+		dev_notice(espi_flash->ctrl->dev, "eSPI flash channel not ready\n");
+		return -EIO;
+	}
+
+	/* Test if TX ready */
+	regmap_read(espi_ctrl->map, ESPI_FLASH_TX_CTRL, &reg);
+	if (reg & ESPI_FLASH_TX_CTRL_TRIGGER) {
+		dev_notice(espi_flash->ctrl->dev, "eSPI Tx operation still pending\n");
+		return -EBUSY;
+	}
+
+	/*
+	 * common header (i.e. cycle type, tag, and length)
+	 * part is written to HW registers
+	 */
+	addr_be = htonl(addr);
+	memcpy(espi_flash->dma.tx_virt, &addr_be, sizeof(addr_be));
+	if (pkt && pkt_len)
+		memcpy(espi_flash->dma.tx_virt + sizeof(addr_be), pkt, pkt_len);
+
+	dma_wmb();
+
+	spin_lock_irqsave(&espi_flash->spinlock, flags);
+	espi_flash->tx_sts = 0;
+	espi_flash->rx_sts = 0;
+
+	reg = ((cyc << ESPI_FLASH_TX_CTRL_CYC_SHIFT) &
+	       ESPI_FLASH_TX_CTRL_CYC_MASK) |
+	      ((len << ESPI_FLASH_TX_CTRL_LEN_SHIFT) &
+	       ESPI_FLASH_TX_CTRL_LEN_MASK) |
+	      ESPI_FLASH_TX_CTRL_TRIGGER;
+
+	regmap_write(espi_ctrl->map, ESPI_FLASH_TX_CTRL, reg);
+
+	to = msecs_to_jiffies(100);
+	ret = wait_event_interruptible_lock_irq_timeout(
+		espi_flash->wq, espi_flash->tx_sts, espi_flash->spinlock, to);
+	if (ret == -ERESTARTSYS)
+		ret = -EINTR;
+	else if (!ret) {
+		dev_notice(espi_flash->ctrl->dev, "eSPI Tx operation not processed within 100msec\n");
+		ret = -ETIMEDOUT;
+	} else if (espi_flash->tx_sts &
+		   (ESPI_INT_STS_FLASH_TX_ERR | ESPI_INT_STS_FLASH_TX_ABT)) {
+		dev_notice(espi_flash->ctrl->dev, "eSPI Tx operation declined by remote\n");
+
+		ret = -EFAULT;
+	} else
+		ret = 0;
+
+	spin_unlock_irqrestore(&espi_flash->spinlock, flags);
+	return ret;
+}
+
+void aspeed_espi_flash_event(uint32_t sts, struct aspeed_espi_flash *espi_flash)
+{
+	unsigned long flags;
+
+	if (!(sts & ESPI_INT_STS_FLASH_BITS))
+		return;
+
+	spin_lock_irqsave(&espi_flash->spinlock, flags);
+	espi_flash->rx_sts |=
+		sts & (ESPI_INT_STS_FLASH_RX_ABT | ESPI_INT_STS_FLASH_RX_CMPLT);
+	espi_flash->tx_sts |=
+		sts & (ESPI_INT_STS_FLASH_TX_ERR | ESPI_INT_STS_FLASH_TX_ABT |
+		       ESPI_INT_STS_FLASH_TX_CMPLT);
+	spin_unlock_irqrestore(&espi_flash->spinlock, flags);
+	wake_up_interruptible(&espi_flash->wq);
+}
+
+static int aspeed_espi_flash_erase(struct mtd_info *mtd,
+				   struct erase_info *instr)
+{
+	struct aspeed_espi_flash *espi_flash = mtd->priv;
+	int ret = 0;
+
+	/* Sanity checks */
+	if ((uint32_t)instr->len % espi_flash->mtd.erasesize)
+		return -EINVAL;
+
+	if ((uint32_t)instr->addr % espi_flash->mtd.erasesize)
+		return -EINVAL;
+
+	mutex_lock(&espi_flash->lock);
+
+	while (instr->len) {
+		ret = aspeed_espi_flash_put_tx(ESPI_FLASH_ERASE,
+					       espi_flash->erase_mask,
+					       instr->addr, NULL, 0,
+					       espi_flash);
+		if (ret)
+			goto unlock_mtx_n_out;
+
+		ret = aspeed_espi_flash_rx_get_completion(espi_flash);
+		if (ret)
+			goto unlock_mtx_n_out;
+
+		instr->len -= espi_flash->mtd.erasesize;
+		instr->addr += espi_flash->mtd.erasesize;
+	}
+
+unlock_mtx_n_out:
+	instr->fail_addr = instr->addr;
+
+	mutex_unlock(&espi_flash->lock);
+	return ret;
+}
+
+static int aspeed_espi_flash_read(struct mtd_info *mtd, loff_t from, size_t len,
+				  size_t *retlen, u_char *buf)
+{
+	struct aspeed_espi_flash *espi_flash = mtd->priv;
+	uint16_t len_pt, len_rx;
+	size_t pkt_len;
+	uint8_t cyc;
+	int ret = 0;
+
+	mutex_lock(&espi_flash->lock);
+
+	while (len) {
+		len_pt = (len > ESPI_PLD_LEN_MIN) ? ESPI_PLD_LEN_MIN : len;
+
+		ret = aspeed_espi_flash_put_tx(ESPI_FLASH_READ, len_pt, from,
+					       NULL, 0, espi_flash);
+		if (ret)
+			goto unlock_mtx_n_out;
+
+		pkt_len = len_pt;
+		len_rx = 0;
+		cyc = 0;
+		ret = aspeed_espi_flash_rx(&cyc, &len_rx, NULL, buf, &pkt_len,
+					   espi_flash);
+		if (ret)
+			goto unlock_mtx_n_out;
+
+		if (cyc != ESPI_FLASH_SUC_CMPLT_D_ONLY) {
+			dev_notice(espi_flash->ctrl->dev, "eSPI Rx response was not successful\n");
+			ret = -EFAULT;
+			goto unlock_mtx_n_out;
+		}
+		if (pkt_len != len_pt) {
+			dev_notice(espi_flash->ctrl->dev,
+				"eSPI Rx response has unexpected data length\n");
+			ret = -ENODATA;
+			goto unlock_mtx_n_out;
+		}
+
+		len -= len_pt;
+		buf += len_pt;
+		from += len_pt;
+		*retlen += len_pt;
+	}
+
+unlock_mtx_n_out:
+	mutex_unlock(&espi_flash->lock);
+	return ret;
+}
+
+static int aspeed_espi_flash_write(struct mtd_info *mtd, loff_t to, size_t len,
+				   size_t *retlen, const u_char *buf)
+{
+	struct aspeed_espi_flash *espi_flash = mtd->priv;
+	uint16_t len_pt;
+	int ret = 0;
+
+	mutex_lock(&espi_flash->lock);
+
+	while (len) {
+		len_pt = (len > ESPI_PLD_LEN_MIN) ? ESPI_PLD_LEN_MIN : len;
+
+		ret = aspeed_espi_flash_put_tx(ESPI_FLASH_WRITE, len_pt, to,
+					       buf, len_pt, espi_flash);
+		if (ret)
+			goto unlock_mtx_n_out;
+
+		ret = aspeed_espi_flash_rx_get_completion(espi_flash);
+		if (ret)
+			goto unlock_mtx_n_out;
+
+		len -= len_pt;
+		buf += len_pt;
+		to += len_pt;
+		*retlen += len_pt;
+	}
+
+unlock_mtx_n_out:
+	mutex_unlock(&espi_flash->lock);
+	return ret;
+}
+
+void aspeed_espi_flash_enable(struct aspeed_espi_flash *espi_flash)
+{
+	struct aspeed_espi_flash_dma *dma = &espi_flash->dma;
+	struct aspeed_espi_ctrl *espi_ctrl = espi_flash->ctrl;
+
+	regmap_update_bits(espi_ctrl->map, ESPI_CTRL,
+			   ESPI_CTRL_FLASH_SW_MODE_MASK, 0);
+
+	/* Enable DMA transfers */
+	regmap_write(espi_ctrl->map, ESPI_FLASH_TX_DMA, dma->tx_addr);
+	regmap_write(espi_ctrl->map, ESPI_FLASH_RX_DMA, dma->rx_addr);
+	regmap_update_bits(
+		espi_ctrl->map, ESPI_CTRL,
+		ESPI_CTRL_FLASH_TX_DMA_EN | ESPI_CTRL_FLASH_RX_DMA_EN,
+		ESPI_CTRL_FLASH_TX_DMA_EN | ESPI_CTRL_FLASH_RX_DMA_EN);
+
+	/* Enable interrupts */
+	regmap_write(espi_ctrl->map, ESPI_INT_STS, ESPI_INT_STS_FLASH_BITS);
+
+	regmap_update_bits(espi_ctrl->map, ESPI_INT_EN, ESPI_INT_EN_FLASH_BITS,
+			   ESPI_INT_EN_FLASH_BITS);
+
+	/* Set Flash Channel Software Ready */
+	regmap_update_bits(espi_ctrl->map, ESPI_CTRL, ESPI_CTRL_FLASH_SW_RDY,
+			   ESPI_CTRL_FLASH_SW_RDY);
+}
+
+void *aspeed_espi_flash_alloc(struct device *dev,
+			      struct aspeed_espi_ctrl *espi_ctrl)
+{
+	int ret, index;
+	struct aspeed_espi_flash_dma *dma;
+	struct mtd_info *mtd;
+	struct aspeed_espi_flash *espi_flash;
+	struct resource res;
+	u32 reg;
+
+	espi_flash =
+		devm_kzalloc(dev, sizeof(struct aspeed_espi_flash), GFP_KERNEL);
+	if (!espi_flash)
+		return ERR_PTR(-ENOMEM);
+
+	espi_flash->ctrl = espi_ctrl;
+
+	/* Bus lock */
+	mutex_init(&espi_flash->lock);
+
+	init_waitqueue_head(&espi_flash->wq);
+
+	spin_lock_init(&espi_flash->spinlock);
+
+	dma = &espi_flash->dma;
+
+	dma->tx_virt =
+		dma_alloc_coherent(dev, PAGE_SIZE, &dma->tx_addr, GFP_KERNEL);
+	if (!dma->tx_virt) {
+		dev_err(dev, "cannot allocate DMA TX buffer\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	dma->rx_virt =
+		dma_alloc_coherent(dev, PAGE_SIZE, &dma->rx_addr, GFP_KERNEL);
+	if (!dma->rx_virt) {
+		dev_err(dev, "cannot allocate DMA RX buffer\n");
+		return ERR_PTR(-ENOMEM);
+	}
+	index = of_property_match_string(dev->of_node, "reg-names",
+					 "espi_flash");
+	ret = of_address_to_resource(dev->of_node, index, &res);
+	if (ret < 0) {
+		dev_err(dev,
+			"Could not find espi_flash resource block size in devtree\n");
+		return ERR_PTR(-ENODEV);
+	}
+	reg = resource_size(&res);
+	mtd = &espi_flash->mtd;
+	mtd->dev.parent = dev;
+	mtd->size = reg;
+	mtd->flags = MTD_CAP_NORFLASH;
+	mtd->_erase = aspeed_espi_flash_erase;
+	mtd->_read = aspeed_espi_flash_read;
+	mtd->_write = aspeed_espi_flash_write;
+	mtd->type = MTD_NORFLASH;
+	mtd->name = "espi-flash-mafs";
+
+	regmap_read(espi_ctrl->map, ESPI_CH3_CAP_N_CONF, &reg);
+	reg = (reg & ESPI_CH3_CAP_N_CONF_ERASE_MASK) >>
+	      ESPI_CH3_CAP_N_CONF_ERASE_SHIFT;
+	espi_flash->erase_mask = reg;
+	switch (reg) {
+	case ESPI_CH3_CAP_N_CONF_ERASE_SIZE_4KB:
+	case ESPI_CH3_CAP_N_CONF_ERASE_SIZE_4KB_64KB:
+		mtd->erasesize = 0x1000;
+		espi_flash->erase_mask = 1;
+		break;
+	case ESPI_CH3_CAP_N_CONF_ERASE_SIZE_64KB:
+		mtd->erasesize = 0x10000;
+		break;
+	case ESPI_CH3_CAP_N_CONF_ERASE_SIZE_128KB:
+		mtd->erasesize = 0x20000;
+		break;
+	case ESPI_CH3_CAP_N_CONF_ERASE_SIZE_256KB:
+		mtd->erasesize = 0x40000;
+		break;
+	default:
+		dev_notice(dev, "Unknown erase size %x\n", reg);
+		return ERR_PTR(-ENODEV);
+	}
+
+	mtd->writesize = 1;
+	mtd->owner = THIS_MODULE;
+	mtd->priv = espi_flash;
+
+	ret = mtd_device_register(mtd, NULL, 0);
+	if (ret) {
+		dev_notice(dev, "aspeed-espi-mtd: Failed to register mtd device\n");
+		return ERR_PTR(ret);
+	}
+
+	aspeed_espi_flash_enable(espi_flash);
+	return espi_flash;
+}
+
+void aspeed_espi_flash_free(struct device *dev,
+			    struct aspeed_espi_flash *espi_flash)
+{
+	struct aspeed_espi_flash_dma *dma = &espi_flash->dma;
+
+	dma_free_coherent(dev, PAGE_SIZE, dma->tx_virt, dma->tx_addr);
+	dma_free_coherent(dev, PAGE_SIZE, dma->rx_virt, dma->rx_addr);
+
+	mtd_device_unregister(&espi_flash->mtd);
+}
diff --git a/drivers/soc/aspeed/aspeed-espi-flash.h b/drivers/soc/aspeed/aspeed-espi-flash.h
new file mode 100644
index 000000000000..08d0a79796e2
--- /dev/null
+++ b/drivers/soc/aspeed/aspeed-espi-flash.h
@@ -0,0 +1,71 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2024 Aspeed Technology Inc.
+ */
+#ifndef _ASPEED_ESPI_FLASH_H_
+#define _ASPEED_ESPI_FLASH_H_
+
+#include <linux/mtd/mtd.h>
+
+/*
+ * eSPI cycle type encoding
+ *
+ * Section 5.1 Cycle Types and Packet Format,
+ * Intel eSPI Interface Base Specification, Rev 1.0, Jan. 2016.
+ */
+#define ESPI_FLASH_READ                 0x00
+#define ESPI_FLASH_WRITE                0x01
+#define ESPI_FLASH_ERASE                0x02
+#define ESPI_FLASH_SUC_CMPLT            0x06
+#define ESPI_FLASH_SUC_CMPLT_D_MIDDLE   0x09
+#define ESPI_FLASH_SUC_CMPLT_D_FIRST    0x0b
+#define ESPI_FLASH_SUC_CMPLT_D_LAST     0x0d
+#define ESPI_FLASH_SUC_CMPLT_D_ONLY     0x0f
+#define ESPI_FLASH_UNSUC_CMPLT          0x0c
+#define ESPI_FLASH_UNSUC_CMPLT_ONLY     0x0e
+
+/*
+ * we choose the longest header and the max payload size
+ * based on the Intel specification to define the maximum
+ * eSPI packet length
+ */
+#define ESPI_PLD_LEN_MIN        (1UL << 6)
+#define ESPI_PLD_LEN_MAX        (1UL << 12)
+
+
+enum aspeed_espi_flash_safs_mode {
+	SAFS_MODE_MIX,
+	SAFS_MODE_SW,
+	SAFS_MODE_HW,
+	SAFS_MODES,
+};
+
+struct aspeed_espi_flash_dma {
+	void *tx_virt;
+	dma_addr_t tx_addr;
+	void *rx_virt;
+	dma_addr_t rx_addr;
+};
+
+struct aspeed_espi_flash {
+
+	unsigned short		page_offset;	/* offset in flash address */
+	unsigned int		page_size;	   /* of bytes per page */
+	struct mutex			lock;
+	struct aspeed_espi_flash_dma	dma;
+	struct mtd_info			mtd;
+	struct aspeed_espi_ctrl		*ctrl;
+	uint8_t				erase_mask;
+	uint32_t			tx_sts;
+	uint32_t			rx_sts;
+	wait_queue_head_t		wq;
+	spinlock_t			spinlock;
+};
+
+void aspeed_espi_flash_event(uint32_t sts, struct aspeed_espi_flash *espi_flash);
+void aspeed_espi_flash_enable(struct aspeed_espi_flash *espi_flash);
+void *aspeed_espi_flash_alloc(struct device *dev, struct aspeed_espi_ctrl *espi_ctrl);
+void aspeed_espi_flash_free(struct device *dev, struct aspeed_espi_flash *espi_flash);
+
+#endif
+