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Subject[PATCH v1] eSPI: add Aspeed AST2500 eSPI driver to boot a host with PCH runs on eSPI
Date
When PCH works under eSPI mode, the PMC (Power Management Controller) in
PCH is waiting for SUS_ACK from BMC after it alerts SUS_WARN. It is in
dead loop if no SUS_ACK assert. This is the basic requirement for the BMC
works as eSPI slave.

Also for the host power on / off actions, from BMC side, the following VW
(Virtual Wire) messages are done in firmware:
1. SLAVE_BOOT_LOAD_DONE / SLAVE_BOOT_LOAD_STATUS
2. SUS_ACK
3. OOB_RESET_ACK
4. HOST_RESET_ACK

Signed-off-by: Haiyue Wang <haiyue.wang@linux.intel.com>
---
.../devicetree/bindings/misc/aspeed-espi-slave.txt | 20 ++
Documentation/misc-devices/espi-slave.rst | 114 +++++++++
drivers/misc/Kconfig | 11 +
drivers/misc/Makefile | 1 +
drivers/misc/aspeed-espi-slave.c | 266 +++++++++++++++++++++
5 files changed, 412 insertions(+)
create mode 100644 Documentation/devicetree/bindings/misc/aspeed-espi-slave.txt
create mode 100644 Documentation/misc-devices/espi-slave.rst
create mode 100644 drivers/misc/aspeed-espi-slave.c

diff --git a/Documentation/devicetree/bindings/misc/aspeed-espi-slave.txt b/Documentation/devicetree/bindings/misc/aspeed-espi-slave.txt
new file mode 100644
index 0000000..35da26f
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/aspeed-espi-slave.txt
@@ -0,0 +1,20 @@
+Aspeed eSPI Slave Controller
+
+Required properties:
+ - compatible: must be one of:
+ - "aspeed,ast2500-espi-slave"
+
+ - reg: physical base address of the controller and length of memory mapped
+ region
+
+ - interrupts: interrupt generated by the controller
+
+Example:
+
+ espi: espi@1e6ee000 {
+ compatible = "aspeed,ast2500-espi-slave";
+ reg = <0x1e6ee000 0x100>;
+ interrupts = <23>;
+ status = "disabled";
+};
+
diff --git a/Documentation/misc-devices/espi-slave.rst b/Documentation/misc-devices/espi-slave.rst
new file mode 100644
index 0000000..405b619
--- /dev/null
+++ b/Documentation/misc-devices/espi-slave.rst
@@ -0,0 +1,114 @@
+eSPI Slave
+==========
+
+The PCH (**eSPI master**) provides the eSPI to support connection of a
+BMC (**eSPI slave**) to the platform.
+
+The LPC and eSPI interfaces are mutually exclusive. Both use the same
+pins, but on power-up, a HW strap determines if the eSPI or the LPC bus
+is operational. Once selected, it’s not possible to change to the other
+interface.
+
+``eSPI Channels and Supported Transactions``
+ +------+---------------------+----------------------+--------------------+
+ | CH # | Channel | Posted Cycles | Non-Posted Cycles |
+ +======+=====================+======================+====================+
+ | 0 | Peripheral | Memory Write, | Memory Read, |
+ | | | Completions | I/O Read/Write |
+ +------+---------------------+----------------------+--------------------+
+ | 1 | Virtual Wire | Virtual Wire GET/PUT | N/A |
+ +------+---------------------+----------------------+--------------------+
+ | 2 | Out-of-Band Message | SMBus Packet GET/PUT | N/A |
+ +------+---------------------+----------------------+--------------------+
+ | 3 | Flash Access | N/A | Flash Read, Write, |
+ | | | | Erase |
+ +------+---------------------+----------------------+--------------------+
+ | N/A | General | Register Accesses | N/A |
+ +------+---------------------+----------------------+--------------------+
+
+Virtual Wire Channel (Channel 1) Overview
+-----------------------------------------
+
+The Virtual Wire channel uses a standard message format to communicate
+several types of signals between the components on the platform::
+
+ - Sideband and GPIO Pins: System events and other dedicated signals
+ between the PCH and eSPI slave. These signals are tunneled between the
+ two components over eSPI.
+
+ - Serial IRQ Interrupts: Interrupts are tunneled from the eSPI slave to
+ the PCH. Both edge and triggered interrupts are supported.
+
+When PCH runs on eSPI mode, from BMC side, the following VW messages are
+done in firmware::
+
+ 1. SLAVE_BOOT_LOAD_DONE / SLAVE_BOOT_LOAD_STATUS
+ 2. SUS_ACK
+ 3. OOB_RESET_ACK
+ 4. HOST_RESET_ACK
+
+``eSPI Virtual Wires (VW)``
+ +----------------------+---------+---------------------------------------+
+ |Virtual Wire |PCH Pin |Comments |
+ | |Direction| |
+ +======================+=========+=======================================+
+ |SUS_WARN# |Output |PCH pin is a GPIO when eSPI is enabled.|
+ | | |eSPI controller receives as VW message.|
+ +----------------------+---------+---------------------------------------+
+ |SUS_ACK# |Input |PCH pin is a GPIO when eSPI is enabled.|
+ | | |eSPI controller receives as VW message.|
+ +----------------------+---------+---------------------------------------+
+ |SLAVE_BOOT_LOAD_DONE |Input |Sent when the BMC has completed its |
+ | | |boot process as an indication to |
+ | | |eSPI-MC to continue with the G3 to S0 |
+ | | |exit. |
+ | | |The eSPI Master waits for the assertion|
+ | | |of this virtual wire before proceeding |
+ | | |with the SLP_S5# deassertion. |
+ | | |The intent is that it is never changed |
+ | | |except on a G3 exit - it is reset on a |
+ | | |G3 entry. |
+ +----------------------+---------+---------------------------------------+
+ |SLAVE_BOOT_LOAD_STATUS|Input |Sent upon completion of the Slave Boot |
+ | | |Load from the attached flash. A stat of|
+ | | |1 indicates that the boot code load was|
+ | | |successful and that the integrity of |
+ | | |the image is intact. |
+ +----------------------+---------+---------------------------------------+
+ |HOST_RESET_WARN |Output |Sent from the MC just before the Host |
+ | | |is about to enter reset. Upon receiving|
+ | | |, the BMC must flush and quiesce its |
+ | | |upstream Peripheral Channel request |
+ | | |queues and assert HOST_RESET_ACK VWire.|
+ | | |The MC subsequently completes any |
+ | | |outstanding posted transactions or |
+ | | |completions and then disables the |
+ | | |Peripheral Channel via a write to |
+ | | |the Slave's Configuration Register. |
+ +----------------------+---------+---------------------------------------+
+ |HOST_RESET_ACK |Input |ACK for the HOST_RESET_WARN message |
+ +----------------------+---------+---------------------------------------+
+ |OOB_RESET_WARN |Output |Sent from the MC just before the OOB |
+ | | |processor is about to enter reset. Upon|
+ | | |receiving, the BMC must flush and |
+ | | |quiesce its OOB Channel upstream |
+ | | |request queues and assert OOB_RESET_ACK|
+ | | |VWire. The-MC subsequently completes |
+ | | |any outstanding posted transactions or |
+ | | |completions and then disables the OOB |
+ | | |Channel via a write to the Slave's |
+ | | |Configuration Register. |
+ +----------------------+---------+---------------------------------------+
+ |OOB_RESET_ACK |Input |ACK for OOB_RESET_WARN message |
+ +----------------------+---------+---------------------------------------+
+
+`Intel C620 Series Chipset Platform Controller Hub
+<https://www.intel.com/content/www/us/en/chipsets/c620-series-chipset-datasheet.html>`_
+
+ -- 17. Enhanced Serial Peripheral Interface
+
+
+`Enhanced Serial Peripheral Interface (eSPI)
+- Interface Base Specification (for Client and Server Platforms)
+<https://www.intel.com/content/dam/support/us/en/documents/software/chipset-software/327432-004_espi_base_specification_rev1.0.pdf>`_
+
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index f1a5c23..fec5783 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -471,6 +471,17 @@ config VEXPRESS_SYSCFG
ARM Ltd. Versatile Express uses specialised platform configuration
bus. System Configuration interface is one of the possible means
of generating transactions on this bus.
+config ASPEED_ESPI_SLAVE
+ depends on ARCH_ASPEED || COMPILE_TEST
+ select REGMAP_MMIO
+ tristate "Aspeed ast2500 eSPI slave device"
+ ---help---
+ This allows host to access Baseboard Management Controller (BMC) over the
+ Enhanced Serial Peripheral Interface (eSPI) bus, which replaces the Low Pin
+ Count (LPC) bus.
+
+ Its interface supports peripheral, virtual wire, out-of-band, and flash
+ sharing channels.

config ASPEED_LPC_CTRL
depends on (ARCH_ASPEED || COMPILE_TEST) && REGMAP && MFD_SYSCON
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 5ca5f64..a1081f4 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -52,6 +52,7 @@ obj-$(CONFIG_GENWQE) += genwqe/
obj-$(CONFIG_ECHO) += echo/
obj-$(CONFIG_VEXPRESS_SYSCFG) += vexpress-syscfg.o
obj-$(CONFIG_CXL_BASE) += cxl/
+obj-$(CONFIG_ASPEED_ESPI_SLAVE) += aspeed-espi-slave.o
obj-$(CONFIG_ASPEED_LPC_CTRL) += aspeed-lpc-ctrl.o
obj-$(CONFIG_ASPEED_LPC_SNOOP) += aspeed-lpc-snoop.o
obj-$(CONFIG_PCI_ENDPOINT_TEST) += pci_endpoint_test.o
diff --git a/drivers/misc/aspeed-espi-slave.c b/drivers/misc/aspeed-espi-slave.c
new file mode 100644
index 0000000..a0359cb
--- /dev/null
+++ b/drivers/misc/aspeed-espi-slave.c
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2012-2020, ASPEED Technology Inc.
+// Copyright (c) 2015-2017, Intel Corporation.
+
+#include <linux/atomic.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/poll.h>
+#include <linux/regmap.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/timer.h>
+
+#define DEVICE_NAME "aspeed-espi-slave"
+
+
+#define ESPI_CTRL 0x00
+#define ESPI_CTRL_SW_RESET GENMASK(31, 24)
+#define ESPI_CTRL_OOB_CHRDY BIT(4)
+#define ESPI_ISR 0x08
+#define ESPI_ISR_HW_RESET BIT(31)
+#define ESPI_ISR_VW_SYS_EVT1 BIT(22)
+#define ESPI_ISR_VW_SYS_EVT BIT(8)
+#define ESPI_IER 0x0C
+
+#define ESPI_SYS_IER 0x94
+#define ESPI_SYS_EVENT 0x98
+#define ESPI_SYS_INT_T0 0x110
+#define ESPI_SYS_INT_T1 0x114
+#define ESPI_SYS_INT_T2 0x118
+#define ESPI_SYS_ISR 0x11C
+#define ESPI_SYSEVT_HOST_RST_ACK BIT(27)
+#define ESPI_SYSEVT_SLAVE_BOOT_STATUS BIT(23)
+#define ESPI_SYSEVT_SLAVE_BOOT_DONE BIT(20)
+#define ESPI_SYSEVT_OOB_RST_ACK BIT(16)
+#define ESPI_SYSEVT_HOST_RST_WARN BIT(8)
+#define ESPI_SYSEVT_OOB_RST_WARN BIT(6)
+#define ESPI_SYSEVT_PLT_RST_N BIT(5)
+
+#define ESPI_SYS1_IER 0x100
+#define ESPI_SYS1_EVENT 0x104
+#define ESPI_SYS1_INT_T0 0x120
+#define ESPI_SYS1_INT_T1 0x124
+#define ESPI_SYS1_INT_T2 0x128
+#define ESPI_SYS1_ISR 0x12C
+#define ESPI_SYSEVT1_SUS_ACK BIT(20)
+#define ESPI_SYSEVT1_SUS_WARN BIT(0)
+
+
+struct aspeed_espi_slave_data {
+ struct regmap *map;
+};
+
+static void aspeed_espi_slave_sys_event(struct aspeed_espi_slave_data *priv)
+{
+ u32 sts, evt;
+
+ if (regmap_read(priv->map, ESPI_SYS_ISR, &sts) != 0 ||
+ regmap_read(priv->map, ESPI_SYS_EVENT, &evt) != 0)
+ return;
+
+ if (sts & ESPI_SYSEVT_HOST_RST_WARN)
+ regmap_update_bits_base(priv->map, ESPI_SYS_EVENT,
+ ESPI_SYSEVT_HOST_RST_ACK,
+ evt & ESPI_SYSEVT_HOST_RST_WARN ?
+ ESPI_SYSEVT_HOST_RST_ACK : 0,
+ NULL, false, true);
+
+ if (sts & ESPI_SYSEVT_OOB_RST_WARN)
+ regmap_update_bits_base(priv->map, ESPI_SYS_EVENT,
+ ESPI_SYSEVT_OOB_RST_ACK,
+ evt & ESPI_SYSEVT_OOB_RST_WARN ?
+ ESPI_SYSEVT_OOB_RST_ACK : 0,
+ NULL, false, true);
+
+ regmap_write(priv->map, ESPI_SYS_ISR, sts);
+}
+
+static void aspeed_espi_slave_sys1_event(struct aspeed_espi_slave_data *priv)
+{
+ u32 sts;
+
+ if (regmap_read(priv->map, ESPI_SYS1_ISR, &sts) != 0)
+ return;
+
+ if (sts & ESPI_SYSEVT1_SUS_WARN)
+ regmap_update_bits_base(priv->map, ESPI_SYS1_EVENT,
+ ESPI_SYSEVT1_SUS_ACK, ESPI_SYSEVT1_SUS_ACK,
+ NULL, false, true);
+
+ regmap_write(priv->map, ESPI_SYS1_ISR, sts);
+}
+
+static irqreturn_t aspeed_espi_slave_irq(int irq, void *arg)
+{
+ struct aspeed_espi_slave_data *priv = arg;
+ u32 sts;
+
+ if (regmap_read(priv->map, ESPI_ISR, &sts) != 0)
+ return IRQ_NONE;
+
+ if (sts & ESPI_ISR_HW_RESET) {
+ regmap_update_bits_base(priv->map, ESPI_CTRL,
+ ESPI_CTRL_SW_RESET, 0,
+ NULL, false, true);
+ regmap_update_bits_base(priv->map, ESPI_CTRL,
+ ESPI_CTRL_SW_RESET, ESPI_CTRL_SW_RESET,
+ NULL, false, true);
+
+ regmap_update_bits_base(priv->map, ESPI_SYS_EVENT,
+ ESPI_SYSEVT_SLAVE_BOOT_STATUS |
+ ESPI_SYSEVT_SLAVE_BOOT_DONE,
+ ESPI_SYSEVT_SLAVE_BOOT_STATUS |
+ ESPI_SYSEVT_SLAVE_BOOT_DONE,
+ NULL, false, true);
+ }
+
+ if (sts & ESPI_ISR_VW_SYS_EVT)
+ aspeed_espi_slave_sys_event(priv);
+
+ if (sts & ESPI_ISR_VW_SYS_EVT1)
+ aspeed_espi_slave_sys1_event(priv);
+
+ regmap_write(priv->map, ESPI_ISR, sts);
+
+ return IRQ_HANDLED;
+}
+
+
+/* Setup Interrupt Type/Enable of System Event from Master
+ * T2 T1 T0
+ * 1). HOST_RST_WARN : Dual Edge 1 0 0
+ * 2). OOB_RST_WARN : Dual Edge 1 0 0
+ * 3). PLTRST_N : Dual Edge 1 0 0
+ */
+#define ESPI_SYS_INT_T0_SET 0x00000000
+#define ESPI_SYS_INT_T1_SET 0x00000000
+#define ESPI_SYS_INT_T2_SET \
+(ESPI_SYSEVT_HOST_RST_WARN | ESPI_SYSEVT_OOB_RST_WARN | ESPI_SYSEVT_PLT_RST_N)
+#define ESPI_SYS_INT_SET \
+(ESPI_SYSEVT_HOST_RST_WARN | ESPI_SYSEVT_OOB_RST_WARN | ESPI_SYSEVT_PLT_RST_N)
+
+/* Setup Interrupt Type/Enable of System Event 1 from Master
+ * T2 T1 T0
+ * 1). SUS_WARN : Rising Edge 0 0 1
+ */
+#define ESPI_SYS1_INT_T0_SET ESPI_SYSEVT1_SUS_WARN
+#define ESPI_SYS1_INT_T1_SET 0x00000000
+#define ESPI_SYS1_INT_T2_SET 0x00000000
+#define ESPI_SYS1_INT_SET ESPI_SYSEVT1_SUS_WARN
+
+static int aspeed_espi_slave_config_irq(struct aspeed_espi_slave_data *priv,
+ struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ int irq;
+ int rc;
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return irq;
+
+ rc = devm_request_irq(dev, irq, aspeed_espi_slave_irq, IRQF_SHARED,
+ dev_name(dev), priv);
+ if (rc < 0)
+ return rc;
+
+ regmap_update_bits(priv->map, ESPI_CTRL, ESPI_CTRL_OOB_CHRDY,
+ ESPI_CTRL_OOB_CHRDY);
+
+ regmap_write(priv->map, ESPI_SYS_INT_T0, ESPI_SYS_INT_T0_SET);
+ regmap_write(priv->map, ESPI_SYS_INT_T1, ESPI_SYS_INT_T1_SET);
+ regmap_write(priv->map, ESPI_SYS_INT_T2, ESPI_SYS_INT_T2_SET);
+ regmap_write(priv->map, ESPI_SYS_IER, ESPI_SYS_INT_SET);
+
+ regmap_write(priv->map, ESPI_SYS1_INT_T0, ESPI_SYS1_INT_T0_SET);
+ regmap_write(priv->map, ESPI_SYS1_INT_T1, ESPI_SYS1_INT_T1_SET);
+ regmap_write(priv->map, ESPI_SYS1_INT_T2, ESPI_SYS1_INT_T2_SET);
+ regmap_write(priv->map, ESPI_SYS1_IER, ESPI_SYS1_INT_SET);
+
+ regmap_write(priv->map, ESPI_IER, 0xFFFFFFFF);
+
+ return 0;
+}
+
+static void aspeed_espi_slave_boot_ack(struct aspeed_espi_slave_data *priv)
+{
+ u32 evt;
+
+ if (regmap_read(priv->map, ESPI_SYS_EVENT, &evt) == 0 &&
+ (evt & ESPI_SYSEVT_SLAVE_BOOT_STATUS) == 0)
+ regmap_write(priv->map, ESPI_SYS_EVENT, evt |
+ ESPI_SYSEVT_SLAVE_BOOT_STATUS |
+ ESPI_SYSEVT_SLAVE_BOOT_DONE);
+
+ if (regmap_read(priv->map, ESPI_SYS1_EVENT, &evt) == 0 &&
+ (evt & ESPI_SYSEVT1_SUS_WARN) != 0)
+ regmap_write(priv->map, ESPI_SYS1_EVENT, evt |
+ ESPI_SYSEVT1_SUS_ACK);
+}
+
+static const struct regmap_config espi_slave_regmap_cfg = {
+ .reg_bits = 32,
+ .reg_stride = 4,
+ .val_bits = 32,
+ .max_register = ESPI_SYS1_ISR,
+};
+
+static int aspeed_espi_slave_probe(struct platform_device *pdev)
+{
+ struct aspeed_espi_slave_data *priv;
+ struct device *dev = &pdev->dev;
+ struct resource *res;
+ void __iomem *regs;
+ int rc;
+
+ dev_set_name(dev, DEVICE_NAME);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ regs = devm_ioremap_resource(dev, res);
+ if (IS_ERR(regs))
+ return PTR_ERR(regs);
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->map = devm_regmap_init_mmio(dev, regs, &espi_slave_regmap_cfg);
+ if (IS_ERR(priv->map))
+ return PTR_ERR(priv->map);
+
+ rc = aspeed_espi_slave_config_irq(priv, pdev);
+ if (rc)
+ return rc;
+
+ aspeed_espi_slave_boot_ack(priv);
+
+ platform_set_drvdata(pdev, priv);
+
+ return 0;
+}
+
+static const struct of_device_id of_espi_slave_match_table[] = {
+ { .compatible = "aspeed,ast2500-espi-slave" },
+ { }
+};
+
+static struct platform_driver aspeed_espi_slave_driver = {
+ .driver = {
+ .name = DEVICE_NAME,
+ .of_match_table = of_espi_slave_match_table,
+ },
+ .probe = aspeed_espi_slave_probe,
+};
+
+module_platform_driver(aspeed_espi_slave_driver);
+
+MODULE_DEVICE_TABLE(of, of_espi_slave_match_table);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
+MODULE_DESCRIPTION("Linux device interface to the eSPI slave");
--
2.7.4
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