[PATCH v4 0/3] LoongArch: Add Loongson-2K BMC support

[PATCH v4 0/3] LoongArch: Add Loongson-2K BMC support

[Binbin Zhou]

Hi all:

This patch set introduces the Loongson-2K BMC.

It is a PCIe device present on servers similar to the Loongson-3 CPUs.
And it is a multifunctional device (MFD), such as display as a sub-function
of it.

For IPMI, according to the existing design, we use software simulation to
implement the KCS interface registers: Stauts/Command/Data_Out/Data_In.

Also since both host side and BMC side read and write kcs status, we use
fifo pointer to ensure data consistency.

For the display, based on simpledrm, the resolution is read from a fixed
position in the BMC since the hardware does not support auto-detection
of the resolution. Of course, we will try to support multiple
resolutions later, through a vbios-like approach.

Especially, for the BMC reset function, since the display will be
disconnected when BMC reset, we made a special treatment of re-push.

Based on this, I will present it in four patches:
patch-1: BMC device PCI resource allocation.
patch-2: BMC reset function support
patch-3: IPMI implementation

Thanks.

-------
V4:
- Add Reviewed-by tag;
- Change the order of the patches.
Patch (1/3):
  - Fix build warning by lkp: Kconfig tristate -> bool
    - https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
 - Update commit message;
 - Move MFD_LS2K_BMC after MFD_INTEL_M10_BMC_PMCI in Kconfig and
   Makefile.
Patch (2/3):
  - Remove unnecessary newlines;
  - Rename ls2k_bmc_check_pcie_connected() to
    ls2k_bmc_pcie_is_connected();
  - Update comment message.
Patch (3/3):
  - Remove unnecessary newlines.

Link to V3:
https://lore.kernel.org/all/cover.1748505446.git.zhoubinbin@loongson.cn/

V3:
Patch (1/3):
 - Drop "MFD" in title and comment;
 - Fromatting code;
 - Add clearer comments.
Patch (2/3):
 - Rebase linux-ipmi/next tree;
 - Use readx()/writex() to read and write IPMI data instead of structure
   pointer references;
 - CONFIG_LOONGARCH -> MFD_LS2K_BMC;
 - Drop unused output.
Patch (3/3):
 - Inline the ls2k_bmc_gpio_reset_handler() function to ls2k_bmc_pdata_initial();
 - Add clearer comments.
 - Use proper multi-line commentary as per the Coding Style documentation;
 - Define all magic numbers.

Link to V2:
https://lore.kernel.org/all/cover.1747276047.git.zhoubinbin@loongson.cn/

V2:
- Drop ls2kdrm, use simpledrm instead.
Patch (1/3):
 - Use DEFINE_RES_MEM_NAMED/MFD_CELL_RES simplified code;
 - Add resolution fetching due to replacing the original display
   solution with simpledrm; 
 - Add aperture_remove_conflicting_devices() to avoid efifb
   conflict with simpledrm.
Patch (3/3):
 - This part of the function, moved from the original ls2kdrm to mfd;
 - Use set_console to implement the Re-push display function.

Link to V1:
https://lore.kernel.org/all/cover.1735550269.git.zhoubinbin@loongson.cn/

Binbin Zhou (3):
  mfd: ls2kbmc: Introduce Loongson-2K BMC core driver
  mfd: ls2kbmc: Add Loongson-2K BMC reset function support
  ipmi: Add Loongson-2K BMC support

 drivers/char/ipmi/Makefile       |   1 +
 drivers/char/ipmi/ipmi_si.h      |   7 +
 drivers/char/ipmi/ipmi_si_intf.c |   3 +
 drivers/char/ipmi/ipmi_si_ls2k.c | 189 ++++++++++++
 drivers/mfd/Kconfig              |  12 +
 drivers/mfd/Makefile             |   2 +
 drivers/mfd/ls2kbmc-mfd.c        | 485 +++++++++++++++++++++++++++++++
 7 files changed, 699 insertions(+)
 create mode 100644 drivers/char/ipmi/ipmi_si_ls2k.c
 create mode 100644 drivers/mfd/ls2kbmc-mfd.c


base-commit: cd2e103d57e5615f9bb027d772f93b9efd567224
-- 
2.47.1

[PATCH v4 1/3] mfd: ls2kbmc: Introduce Loongson-2K BMC core driver

[Binbin Zhou]

The Loongson-2K Board Management Controller provides an PCIe interface
to the host to access the feature implemented in the BMC.

The BMC is assembled on a server similar to the server machine with
Loongson-3 CPU. It supports multiple sub-devices like DRM or IPMI.

Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Co-developed-by: Chong Qiao <qiaochong@loongson.cn>
Signed-off-by: Chong Qiao <qiaochong@loongson.cn>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
---
 drivers/mfd/Kconfig       |  12 +++
 drivers/mfd/Makefile      |   2 +
 drivers/mfd/ls2kbmc-mfd.c | 156 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 170 insertions(+)
 create mode 100644 drivers/mfd/ls2kbmc-mfd.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 96992af22565..10e3d1728e13 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -2389,6 +2389,18 @@ config MFD_INTEL_M10_BMC_PMCI
 	  additional drivers must be enabled in order to use the functionality
 	  of the device.
 
+config MFD_LS2K_BMC
+	bool "Loongson-2K Board Management Controller Support"
+	depends on LOONGARCH
+	default y if LOONGARCH
+	select MFD_CORE
+	help
+	  Say yes here to add support for the Loongson-2K BMC which is a Board
+	  Management Controller connected to the PCIe bus. The device supports
+	  multiple sub-devices like DRM. This driver provides common support for
+	  accessing the devices; additional drivers must be enabled in order to
+	  use the functionality of the BMC device.
+
 config MFD_QNAP_MCU
 	tristate "QNAP microcontroller unit core driver"
 	depends on SERIAL_DEV_BUS
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 5e5cc279af60..bd4282c36ed2 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -282,6 +282,8 @@ obj-$(CONFIG_MFD_INTEL_M10_BMC_CORE)   += intel-m10-bmc-core.o
 obj-$(CONFIG_MFD_INTEL_M10_BMC_SPI)    += intel-m10-bmc-spi.o
 obj-$(CONFIG_MFD_INTEL_M10_BMC_PMCI)   += intel-m10-bmc-pmci.o
 
+obj-$(CONFIG_MFD_LS2K_BMC)	+= ls2kbmc-mfd.o
+
 obj-$(CONFIG_MFD_ATC260X)	+= atc260x-core.o
 obj-$(CONFIG_MFD_ATC260X_I2C)	+= atc260x-i2c.o
 
diff --git a/drivers/mfd/ls2kbmc-mfd.c b/drivers/mfd/ls2kbmc-mfd.c
new file mode 100644
index 000000000000..310ca70700c0
--- /dev/null
+++ b/drivers/mfd/ls2kbmc-mfd.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Loongson-2K Board Management Controller (BMC) Core Driver.
+ *
+ * Copyright (C) 2024-2025 Loongson Technology Corporation Limited.
+ *
+ * Authors:
+ *	Chong Qiao <qiaochong@loongson.cn>
+ *	Binbin Zhou <zhoubinbin@loongson.cn>
+ */
+
+#include <linux/aperture.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/pci_ids.h>
+#include <linux/platform_data/simplefb.h>
+#include <linux/platform_device.h>
+
+/* LS2K BMC resources */
+#define LS2K_DISPLAY_RES_START		(SZ_16M + SZ_2M)
+#define LS2K_IPMI_RES_SIZE		0x1C
+#define LS2K_IPMI0_RES_START		(SZ_16M + 0xF00000)
+#define LS2K_IPMI1_RES_START		(LS2K_IPMI0_RES_START + LS2K_IPMI_RES_SIZE)
+#define LS2K_IPMI2_RES_START		(LS2K_IPMI1_RES_START + LS2K_IPMI_RES_SIZE)
+#define LS2K_IPMI3_RES_START		(LS2K_IPMI2_RES_START + LS2K_IPMI_RES_SIZE)
+#define LS2K_IPMI4_RES_START		(LS2K_IPMI3_RES_START + LS2K_IPMI_RES_SIZE)
+
+static struct resource ls2k_display_resources[] = {
+	DEFINE_RES_MEM_NAMED(LS2K_DISPLAY_RES_START, SZ_4M, "simpledrm-res"),
+};
+
+static struct resource ls2k_ipmi0_resources[] = {
+	DEFINE_RES_MEM_NAMED(LS2K_IPMI0_RES_START, LS2K_IPMI_RES_SIZE, "ipmi0-res"),
+};
+
+static struct resource ls2k_ipmi1_resources[] = {
+	DEFINE_RES_MEM_NAMED(LS2K_IPMI1_RES_START, LS2K_IPMI_RES_SIZE, "ipmi1-res"),
+};
+
+static struct resource ls2k_ipmi2_resources[] = {
+	DEFINE_RES_MEM_NAMED(LS2K_IPMI2_RES_START, LS2K_IPMI_RES_SIZE, "ipmi2-res"),
+};
+
+static struct resource ls2k_ipmi3_resources[] = {
+	DEFINE_RES_MEM_NAMED(LS2K_IPMI3_RES_START, LS2K_IPMI_RES_SIZE, "ipmi3-res"),
+};
+
+static struct resource ls2k_ipmi4_resources[] = {
+	DEFINE_RES_MEM_NAMED(LS2K_IPMI4_RES_START, LS2K_IPMI_RES_SIZE, "ipmi4-res"),
+};
+
+static struct mfd_cell ls2k_bmc_cells[] = {
+	MFD_CELL_RES("simple-framebuffer", ls2k_display_resources),
+	MFD_CELL_RES("ls2k-ipmi-si", ls2k_ipmi0_resources),
+	MFD_CELL_RES("ls2k-ipmi-si", ls2k_ipmi1_resources),
+	MFD_CELL_RES("ls2k-ipmi-si", ls2k_ipmi2_resources),
+	MFD_CELL_RES("ls2k-ipmi-si", ls2k_ipmi3_resources),
+	MFD_CELL_RES("ls2k-ipmi-si", ls2k_ipmi4_resources),
+};
+
+/*
+ * Currently the Loongson-2K BMC hardware does not have an I2C interface to adapt to the
+ * resolution. We set the resolution by presetting "video=1280x1024-16@2M" to the BMC memory.
+ */
+static int ls2k_bmc_parse_mode(struct pci_dev *pdev, struct simplefb_platform_data *pd)
+{
+	char *mode;
+	int depth, ret;
+
+	/* The last 16M of PCI BAR0 is used to store the resolution string. */
+	mode = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M, SZ_16M);
+	if (!mode)
+		return -ENOMEM;
+
+	/* The resolution field starts with the flag "video=". */
+	if (!strncmp(mode, "video=", 6))
+		mode = mode + 6;
+
+	ret = kstrtoint(strsep(&mode, "x"), 10, &pd->width);
+	if (ret)
+		return ret;
+
+	ret = kstrtoint(strsep(&mode, "-"), 10, &pd->height);
+	if (ret)
+		return ret;
+
+	ret = kstrtoint(strsep(&mode, "@"), 10, &depth);
+	if (ret)
+		return ret;
+
+	pd->stride = pd->width * depth / 8;
+	pd->format = depth == 32 ? "a8r8g8b8" : "r5g6b5";
+
+	return 0;
+}
+
+static int ls2k_bmc_probe(struct pci_dev *dev, const struct pci_device_id *id)
+{
+	struct simplefb_platform_data pd;
+	resource_size_t base;
+	int ret;
+
+	ret = pci_enable_device(dev);
+	if (ret)
+		return ret;
+
+	ret = ls2k_bmc_parse_mode(dev, &pd);
+	if (ret)
+		goto disable_pci;
+
+	ls2k_bmc_cells[0].platform_data = &pd;
+	ls2k_bmc_cells[0].pdata_size = sizeof(pd);
+	base = dev->resource[0].start + LS2K_DISPLAY_RES_START;
+
+	/* Remove conflicting efifb device */
+	ret = aperture_remove_conflicting_devices(base, SZ_4M, "simple-framebuffer");
+	if (ret) {
+		dev_err(&dev->dev, "Failed to removed firmware framebuffers: %d\n", ret);
+		goto disable_pci;
+	}
+
+	return devm_mfd_add_devices(&dev->dev, PLATFORM_DEVID_AUTO,
+				    ls2k_bmc_cells, ARRAY_SIZE(ls2k_bmc_cells),
+				    &dev->resource[0], 0, NULL);
+
+disable_pci:
+	pci_disable_device(dev);
+	return ret;
+}
+
+static void ls2k_bmc_remove(struct pci_dev *dev)
+{
+	pci_disable_device(dev);
+}
+
+static struct pci_device_id ls2k_bmc_devices[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 0x1a05) },
+	{ }
+};
+MODULE_DEVICE_TABLE(pci, ls2k_bmc_devices);
+
+static struct pci_driver ls2k_bmc_driver = {
+	.name = "ls2k-bmc",
+	.id_table = ls2k_bmc_devices,
+	.probe = ls2k_bmc_probe,
+	.remove = ls2k_bmc_remove,
+};
+module_pci_driver(ls2k_bmc_driver);
+
+MODULE_DESCRIPTION("Loongson-2K BMC driver");
+MODULE_AUTHOR("Loongson Technology Corporation Limited");
+MODULE_LICENSE("GPL");
-- 
2.47.1

[PATCH v4 2/3] mfd: ls2kbmc: Add Loongson-2K BMC reset function support

[Binbin Zhou]

Since the display is a sub-function of the Loongson-2K BMC, when the
BMC reset, the entire BMC PCIe is disconnected, including the display
which is interrupted.

Quick overview of the entire LS2K BMC reset process:

There are two types of reset methods: soft reset (BMC-initiated reboot
of IPMI reset command) and BMC watchdog reset (watchdog timeout).

First, regardless of the method, an interrupt is generated (PCIe interrupt
for soft reset/GPIO interrupt for watchdog reset);

Second, during the interrupt process, the system enters bmc_reset_work,
clears the bus/IO/mem resources of the LS7A PCI-E bridge, waits for the BMC
reset to begin, then restores the parent device's PCI configuration space,
waits for the BMC reset to complete, and finally restores the BMC PCI
configuration space.

Display restoration occurs last.

Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Co-developed-by: Chong Qiao <qiaochong@loongson.cn>
Signed-off-by: Chong Qiao <qiaochong@loongson.cn>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
---
 drivers/mfd/ls2kbmc-mfd.c | 329 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 329 insertions(+)

diff --git a/drivers/mfd/ls2kbmc-mfd.c b/drivers/mfd/ls2kbmc-mfd.c
index 310ca70700c0..2c8e86194cb3 100644
--- a/drivers/mfd/ls2kbmc-mfd.c
+++ b/drivers/mfd/ls2kbmc-mfd.c
@@ -10,8 +10,12 @@
  */
 
 #include <linux/aperture.h>
+#include <linux/bitfield.h>
+#include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/init.h>
+#include <linux/iopoll.h>
+#include <linux/kbd_kern.h>
 #include <linux/kernel.h>
 #include <linux/mfd/core.h>
 #include <linux/module.h>
@@ -19,6 +23,8 @@
 #include <linux/pci_ids.h>
 #include <linux/platform_data/simplefb.h>
 #include <linux/platform_device.h>
+#include <linux/stop_machine.h>
+#include <linux/vt_kern.h>
 
 /* LS2K BMC resources */
 #define LS2K_DISPLAY_RES_START		(SZ_16M + SZ_2M)
@@ -29,6 +35,48 @@
 #define LS2K_IPMI3_RES_START		(LS2K_IPMI2_RES_START + LS2K_IPMI_RES_SIZE)
 #define LS2K_IPMI4_RES_START		(LS2K_IPMI3_RES_START + LS2K_IPMI_RES_SIZE)
 
+#define LS7A_PCI_CFG_SIZE		0x100
+
+/* LS7A bridge registers */
+#define LS7A_PCIE_PORT_CTL0		0x0
+#define LS7A_PCIE_PORT_STS1		0xC
+#define LS7A_GEN2_CTL			0x80C
+#define LS7A_SYMBOL_TIMER		0x71C
+
+/* Bits of LS7A_PCIE_PORT_CTL0 */
+#define LS2K_BMC_PCIE_LTSSM_ENABLE	BIT(3)
+
+/* Bits of LS7A_PCIE_PORT_STS1 */
+#define LS2K_BMC_PCIE_LTSSM_STS		GENMASK(5, 0)
+#define LS2K_BMC_PCIE_CONNECTED		0x11
+
+#define LS2K_BMC_PCIE_DELAY_US		1000
+#define LS2K_BMC_PCIE_TIMEOUT_US	1000000
+
+/* Bits of LS7A_GEN2_CTL */
+#define LS7A_GEN2_SPEED_CHANG		BIT(17)
+#define LS7A_CONF_PHY_TX		BIT(18)
+
+/* Bits of LS7A_SYMBOL_TIMER */
+#define LS7A_MASK_LEN_MATCH		BIT(26)
+
+/* Interval between interruptions */
+#define LS2K_BMC_INT_INTERVAL		(60 * HZ)
+
+/* Maximum time to wait for U-Boot and DDR to be ready with ms. */
+#define LS2K_BMC_RESET_WAIT_TIME	10000
+
+/* It's an experience value */
+#define LS7A_BAR0_CHECK_MAX_TIMES	2000
+
+#define LS2K_BMC_RESET_GPIO		14
+#define LOONGSON_GPIO_REG_BASE		0x1FE00500
+#define LOONGSON_GPIO_REG_SIZE		0x18
+#define LOONGSON_GPIO_OEN		0x0
+#define LOONGSON_GPIO_FUNC		0x4
+#define LOONGSON_GPIO_INTPOL		0x10
+#define LOONGSON_GPIO_INTEN		0x14
+
 static struct resource ls2k_display_resources[] = {
 	DEFINE_RES_MEM_NAMED(LS2K_DISPLAY_RES_START, SZ_4M, "simpledrm-res"),
 };
@@ -62,6 +110,274 @@ static struct mfd_cell ls2k_bmc_cells[] = {
 	MFD_CELL_RES("ls2k-ipmi-si", ls2k_ipmi4_resources),
 };
 
+/* Index of the BMC PCI configuration space to be restored at BMC reset. */
+struct ls2k_bmc_pci_data {
+	u32 pci_command;
+	u32 base_address0;
+	u32 interrupt_line;
+};
+
+/* Index of the parent PCI configuration space to be restored at BMC reset. */
+struct ls2k_bmc_bridge_pci_data {
+	u32 pci_command;
+	u32 base_address[6];
+	u32 rom_addreess;
+	u32 interrupt_line;
+	u32 msi_hi;
+	u32 msi_lo;
+	u32 devctl;
+	u32 linkcap;
+	u32 linkctl_sts;
+	u32 symbol_timer;
+	u32 gen2_ctrl;
+};
+
+struct ls2k_bmc_pdata {
+	struct device *dev;
+	struct work_struct bmc_reset_work;
+	struct ls2k_bmc_pci_data bmc_pci_data;
+	struct ls2k_bmc_bridge_pci_data bridge_pci_data;
+};
+
+static bool ls2k_bmc_bar0_addr_is_set(struct pci_dev *ppdev)
+{
+	u32 addr;
+
+	pci_read_config_dword(ppdev, PCI_BASE_ADDRESS_0, &addr);
+
+	return addr & PCI_BASE_ADDRESS_MEM_MASK ? true : false;
+}
+
+static bool ls2k_bmc_pcie_is_connected(struct pci_dev *parent, struct ls2k_bmc_pdata *priv)
+{
+	void __iomem *base;
+	int sts, ret;
+
+	base = pci_iomap(parent, 0, LS7A_PCI_CFG_SIZE);
+	if (!base)
+		return false;
+
+	writel(readl(base + LS7A_PCIE_PORT_CTL0) | LS2K_BMC_PCIE_LTSSM_ENABLE,
+	       base + LS7A_PCIE_PORT_CTL0);
+
+	ret = readl_poll_timeout_atomic(base + LS7A_PCIE_PORT_STS1, sts,
+					(sts & LS2K_BMC_PCIE_LTSSM_STS) == LS2K_BMC_PCIE_CONNECTED,
+					LS2K_BMC_PCIE_DELAY_US, LS2K_BMC_PCIE_TIMEOUT_US);
+	if (ret) {
+		pci_iounmap(parent, base);
+		dev_err(priv->dev, "PCIE train failed status=0x%x\n", sts);
+		return false;
+	}
+
+	pci_iounmap(parent, base);
+	return true;
+}
+
+static void ls2k_bmc_restore_bridge_pci_data(struct pci_dev *parent, struct ls2k_bmc_pdata *priv)
+{
+	int base, i = 0;
+
+	pci_write_config_dword(parent, PCI_COMMAND, priv->bridge_pci_data.pci_command);
+
+	for (base = PCI_BASE_ADDRESS_0; base <= PCI_BASE_ADDRESS_5; base += 4, i++)
+		pci_write_config_dword(parent, base, priv->bridge_pci_data.base_address[i]);
+
+	pci_write_config_dword(parent, PCI_ROM_ADDRESS, priv->bridge_pci_data.rom_addreess);
+	pci_write_config_dword(parent, PCI_INTERRUPT_LINE, priv->bridge_pci_data.interrupt_line);
+
+	pci_write_config_dword(parent, parent->msi_cap + PCI_MSI_ADDRESS_LO,
+			       priv->bridge_pci_data.msi_lo);
+	pci_write_config_dword(parent, parent->msi_cap + PCI_MSI_ADDRESS_HI,
+			       priv->bridge_pci_data.msi_hi);
+	pci_write_config_dword(parent, parent->pcie_cap + PCI_EXP_DEVCTL,
+			       priv->bridge_pci_data.devctl);
+	pci_write_config_dword(parent, parent->pcie_cap + PCI_EXP_LNKCAP,
+			       priv->bridge_pci_data.linkcap);
+	pci_write_config_dword(parent, parent->pcie_cap + PCI_EXP_LNKCTL,
+			       priv->bridge_pci_data.linkctl_sts);
+
+	pci_write_config_dword(parent, LS7A_GEN2_CTL, priv->bridge_pci_data.gen2_ctrl);
+	pci_write_config_dword(parent, LS7A_SYMBOL_TIMER, priv->bridge_pci_data.symbol_timer);
+}
+
+static int ls2k_bmc_recover_pci_data(void *data)
+{
+	struct ls2k_bmc_pdata *priv = data;
+	struct pci_dev *pdev = to_pci_dev(priv->dev);
+	struct pci_dev *parent = pdev->bus->self;
+	u32 i;
+
+	/*
+	 * Clear the bus, io and mem resources of the PCI-E bridge to zero, so that
+	 * the processor can not access the LS2K PCI-E port, to avoid crashing due to
+	 * the lack of return signal from accessing the LS2K PCI-E port.
+	 */
+	pci_write_config_dword(parent, PCI_BASE_ADDRESS_2, 0);
+	pci_write_config_dword(parent, PCI_BASE_ADDRESS_3, 0);
+	pci_write_config_dword(parent, PCI_BASE_ADDRESS_4, 0);
+
+	/*
+	 * When the LS2K BMC is reset, the LS7A PCI-E port is also reset, and its PCI
+	 * BAR0 register is cleared. Due to the time gap between the GPIO interrupt
+	 * generation and the LS2K BMC reset, the LS7A PCI BAR0 register is read to
+	 * determine whether the reset has begun.
+	 */
+	for (i = LS7A_BAR0_CHECK_MAX_TIMES; i > 0 ; i--) {
+		if (!ls2k_bmc_bar0_addr_is_set(parent))
+			break;
+		mdelay(1);
+	};
+
+	if (i == 0)
+		return false;
+
+	ls2k_bmc_restore_bridge_pci_data(parent, priv);
+
+	/* Check if PCI-E is connected */
+	if (!ls2k_bmc_pcie_is_connected(parent, priv))
+		return false;
+
+	/* Waiting for U-Boot and DDR ready */
+	mdelay(LS2K_BMC_RESET_WAIT_TIME);
+	if (!ls2k_bmc_bar0_addr_is_set(parent))
+		return false;
+
+	/* Restore LS2K BMC PCI-E config data */
+	pci_write_config_dword(pdev, PCI_COMMAND, priv->bmc_pci_data.pci_command);
+	pci_write_config_dword(pdev, PCI_BASE_ADDRESS_0, priv->bmc_pci_data.base_address0);
+	pci_write_config_dword(pdev, PCI_INTERRUPT_LINE, priv->bmc_pci_data.interrupt_line);
+
+	return 0;
+}
+
+static void ls2k_bmc_events_fn(struct work_struct *work)
+{
+	struct ls2k_bmc_pdata *priv = container_of(work, struct ls2k_bmc_pdata, bmc_reset_work);
+
+	/*
+	 * The PCI-E is lost when the BMC resets, at which point access to the PCI-E
+	 * from other CPUs is suspended to prevent a crash.
+	 */
+	stop_machine(ls2k_bmc_recover_pci_data, priv, NULL);
+
+#ifdef CONFIG_VT
+	/* Re-push the display due to previous PCI-E loss. */
+	set_console(vt_move_to_console(MAX_NR_CONSOLES - 1, 1));
+#endif
+}
+
+static irqreturn_t ls2k_bmc_interrupt(int irq, void *arg)
+{
+	struct ls2k_bmc_pdata *priv = arg;
+	static unsigned long last_jiffies;
+
+	if (system_state != SYSTEM_RUNNING)
+		return IRQ_HANDLED;
+
+	/* Skip interrupt in LS2K_BMC_INT_INTERVAL */
+	if (time_after(jiffies, last_jiffies + LS2K_BMC_INT_INTERVAL)) {
+		schedule_work(&priv->bmc_reset_work);
+		last_jiffies = jiffies;
+	}
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Saves the BMC parent device (LS7A) and its own PCI configuration space registers
+ * that need to be restored after BMC reset.
+ */
+static void ls2k_bmc_save_pci_data(struct pci_dev *pdev, struct ls2k_bmc_pdata *priv)
+{
+	struct pci_dev *parent = pdev->bus->self;
+	int base, i = 0;
+
+	pci_read_config_dword(parent, PCI_COMMAND, &priv->bridge_pci_data.pci_command);
+
+	for (base = PCI_BASE_ADDRESS_0; base <= PCI_BASE_ADDRESS_5; base += 4, i++)
+		pci_read_config_dword(parent, base, &priv->bridge_pci_data.base_address[i]);
+
+	pci_read_config_dword(parent, PCI_ROM_ADDRESS, &priv->bridge_pci_data.rom_addreess);
+	pci_read_config_dword(parent, PCI_INTERRUPT_LINE, &priv->bridge_pci_data.interrupt_line);
+
+	pci_read_config_dword(parent, parent->msi_cap + PCI_MSI_ADDRESS_LO,
+			      &priv->bridge_pci_data.msi_lo);
+	pci_read_config_dword(parent, parent->msi_cap + PCI_MSI_ADDRESS_HI,
+			      &priv->bridge_pci_data.msi_hi);
+
+	pci_read_config_dword(parent, parent->pcie_cap + PCI_EXP_DEVCTL,
+			      &priv->bridge_pci_data.devctl);
+	pci_read_config_dword(parent, parent->pcie_cap + PCI_EXP_LNKCAP,
+			      &priv->bridge_pci_data.linkcap);
+	pci_read_config_dword(parent, parent->pcie_cap + PCI_EXP_LNKCTL,
+			      &priv->bridge_pci_data.linkctl_sts);
+
+	pci_read_config_dword(parent, LS7A_GEN2_CTL, &priv->bridge_pci_data.gen2_ctrl);
+	priv->bridge_pci_data.gen2_ctrl |= FIELD_PREP(LS7A_GEN2_SPEED_CHANG, 0x1)
+					| FIELD_PREP(LS7A_CONF_PHY_TX, 0x0);
+
+	pci_read_config_dword(parent, LS7A_SYMBOL_TIMER, &priv->bridge_pci_data.symbol_timer);
+	priv->bridge_pci_data.symbol_timer |= LS7A_MASK_LEN_MATCH;
+
+	pci_read_config_dword(pdev, PCI_COMMAND, &priv->bmc_pci_data.pci_command);
+	pci_read_config_dword(pdev, PCI_BASE_ADDRESS_0, &priv->bmc_pci_data.base_address0);
+	pci_read_config_dword(pdev, PCI_INTERRUPT_LINE, &priv->bmc_pci_data.interrupt_line);
+}
+
+static int ls2k_bmc_pdata_initial(struct pci_dev *pdev, struct ls2k_bmc_pdata *priv)
+{
+	int gsi = 16 + (LS2K_BMC_RESET_GPIO & 7);
+	void __iomem *gpio_base;
+	int irq, ret;
+
+	ls2k_bmc_save_pci_data(pdev, priv);
+
+	INIT_WORK(&priv->bmc_reset_work, ls2k_bmc_events_fn);
+
+	ret = devm_request_irq(&pdev->dev, pdev->irq, ls2k_bmc_interrupt,
+			       IRQF_SHARED | IRQF_TRIGGER_FALLING, "ls2kbmc pcie", priv);
+	if (ret) {
+		dev_err(priv->dev, "LS2KBMC PCI-E request_irq(%d) failed\n", pdev->irq);
+		return ret;
+	}
+
+	/*
+	 * Since Loongson-3 hardware does not support GPIO interrupt cascade,
+	 * chip->gpio_to_irq() cannot be implemented, here acpi_register_gsi() is used
+	 * to get the GPIO irq.
+	 * The GPIO interrupt is a watchdog interrupt that is triggered when the BMC resets.
+	 */
+	irq = acpi_register_gsi(NULL, gsi, ACPI_EDGE_SENSITIVE, ACPI_ACTIVE_LOW);
+	if (irq < 0)
+		return irq;
+
+	gpio_base = ioremap(LOONGSON_GPIO_REG_BASE, LOONGSON_GPIO_REG_SIZE);
+	if (!gpio_base) {
+		ret = PTR_ERR(gpio_base);
+		goto acpi_failed;
+	}
+
+	writel(readl(gpio_base + LOONGSON_GPIO_OEN) | BIT(LS2K_BMC_RESET_GPIO),
+	       gpio_base + LOONGSON_GPIO_OEN);
+	writel(readl(gpio_base + LOONGSON_GPIO_FUNC) & ~BIT(LS2K_BMC_RESET_GPIO),
+	       gpio_base + LOONGSON_GPIO_FUNC);
+	writel(readl(gpio_base + LOONGSON_GPIO_INTPOL) & ~BIT(LS2K_BMC_RESET_GPIO),
+	       gpio_base + LOONGSON_GPIO_INTPOL);
+	writel(readl(gpio_base + LOONGSON_GPIO_INTEN) | BIT(LS2K_BMC_RESET_GPIO),
+	       gpio_base + LOONGSON_GPIO_INTEN);
+
+	ret = devm_request_irq(priv->dev, irq, ls2k_bmc_interrupt,
+			       IRQF_SHARED | IRQF_TRIGGER_FALLING, "ls2kbmc gpio", priv);
+	if (ret)
+		dev_err(priv->dev, "LS2KBMC GPIO request_irq(%d) failed\n", irq);
+
+	iounmap(gpio_base);
+
+acpi_failed:
+	acpi_unregister_gsi(gsi);
+	return ret;
+}
+
 /*
  * Currently the Loongson-2K BMC hardware does not have an I2C interface to adapt to the
  * resolution. We set the resolution by presetting "video=1280x1024-16@2M" to the BMC memory.
@@ -101,6 +417,7 @@ static int ls2k_bmc_parse_mode(struct pci_dev *pdev, struct simplefb_platform_da
 static int ls2k_bmc_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
 	struct simplefb_platform_data pd;
+	struct ls2k_bmc_pdata *priv;
 	resource_size_t base;
 	int ret;
 
@@ -108,6 +425,18 @@ static int ls2k_bmc_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if (ret)
 		return ret;
 
+	priv = devm_kzalloc(&dev->dev, sizeof(*priv), GFP_KERNEL);
+	if (IS_ERR(priv)) {
+		ret = -ENOMEM;
+		goto disable_pci;
+	}
+
+	priv->dev = &dev->dev;
+
+	ret = ls2k_bmc_pdata_initial(dev, priv);
+	if (ret)
+		goto disable_pci;
+
 	ret = ls2k_bmc_parse_mode(dev, &pd);
 	if (ret)
 		goto disable_pci;
-- 
2.47.1

[PATCH v4 3/3] ipmi: Add Loongson-2K BMC support

[Binbin Zhou]

This patch adds Loongson-2K BMC IPMI support.

According to the existing design, we use software simulation to
implement the KCS interface registers: Stauts/Command/Data_Out/Data_In.

Also since both host side and BMC side read and write kcs status, fifo flag
is used to ensure data consistency.

The single KCS message block is as follows:

+-------------------------------------------------------------------------+
|FIFO flags| KCS register data | CMD data | KCS version | WR REQ | WR ACK |
+-------------------------------------------------------------------------+

Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Co-developed-by: Chong Qiao <qiaochong@loongson.cn>
Signed-off-by: Chong Qiao <qiaochong@loongson.cn>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
---
 drivers/char/ipmi/Makefile       |   1 +
 drivers/char/ipmi/ipmi_si.h      |   7 ++
 drivers/char/ipmi/ipmi_si_intf.c |   3 +
 drivers/char/ipmi/ipmi_si_ls2k.c | 189 +++++++++++++++++++++++++++++++
 4 files changed, 200 insertions(+)
 create mode 100644 drivers/char/ipmi/ipmi_si_ls2k.c

diff --git a/drivers/char/ipmi/Makefile b/drivers/char/ipmi/Makefile
index e0944547c9d0..17308dd6be20 100644
--- a/drivers/char/ipmi/Makefile
+++ b/drivers/char/ipmi/Makefile
@@ -8,6 +8,7 @@ ipmi_si-y := ipmi_si_intf.o ipmi_kcs_sm.o ipmi_smic_sm.o ipmi_bt_sm.o \
 	ipmi_si_mem_io.o
 ipmi_si-$(CONFIG_HAS_IOPORT) += ipmi_si_port_io.o
 ipmi_si-$(CONFIG_PCI) += ipmi_si_pci.o
+ipmi_si-$(CONFIG_MFD_LS2K_BMC) += ipmi_si_ls2k.o
 ipmi_si-$(CONFIG_PARISC) += ipmi_si_parisc.o
 
 obj-$(CONFIG_IPMI_HANDLER) += ipmi_msghandler.o
diff --git a/drivers/char/ipmi/ipmi_si.h b/drivers/char/ipmi/ipmi_si.h
index 508c3fd45877..f38ea4f4c891 100644
--- a/drivers/char/ipmi/ipmi_si.h
+++ b/drivers/char/ipmi/ipmi_si.h
@@ -101,6 +101,13 @@ void ipmi_si_pci_shutdown(void);
 static inline void ipmi_si_pci_init(void) { }
 static inline void ipmi_si_pci_shutdown(void) { }
 #endif
+#ifdef CONFIG_MFD_LS2K_BMC
+void ipmi_si_ls2k_init(void);
+void ipmi_si_ls2k_shutdown(void);
+#else
+static inline void ipmi_si_ls2k_init(void) { }
+static inline void ipmi_si_ls2k_shutdown(void) { }
+#endif
 #ifdef CONFIG_PARISC
 void ipmi_si_parisc_init(void);
 void ipmi_si_parisc_shutdown(void);
diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 7fe891783a37..c13d5132fffc 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -2120,6 +2120,8 @@ static int __init init_ipmi_si(void)
 
 	ipmi_si_pci_init();
 
+	ipmi_si_ls2k_init();
+
 	ipmi_si_parisc_init();
 
 	mutex_lock(&smi_infos_lock);
@@ -2334,6 +2335,8 @@ static void cleanup_ipmi_si(void)
 
 	ipmi_si_pci_shutdown();
 
+	ipmi_si_ls2k_shutdown();
+
 	ipmi_si_parisc_shutdown();
 
 	ipmi_si_platform_shutdown();
diff --git a/drivers/char/ipmi/ipmi_si_ls2k.c b/drivers/char/ipmi/ipmi_si_ls2k.c
new file mode 100644
index 000000000000..7b360056f9c5
--- /dev/null
+++ b/drivers/char/ipmi/ipmi_si_ls2k.c
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for Loongson-2K BMC IPMI
+ *
+ * Copyright (C) 2024-2025 Loongson Technology Corporation Limited.
+ *
+ * Authors:
+ *	Chong Qiao <qiaochong@loongson.cn>
+ *	Binbin Zhou <zhoubinbin@loongson.cn>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/ioport.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#include "ipmi_si.h"
+
+#define LS2K_KCS_FIFO_IBFH	0x0
+#define LS2K_KCS_FIFO_IBFT	0x1
+#define LS2K_KCS_FIFO_OBFH	0x2
+#define LS2K_KCS_FIFO_OBFT	0x3
+
+/* KCS registers */
+#define LS2K_KCS_REG_STS	0x4
+#define LS2K_KCS_REG_DATA_OUT	0x5
+#define LS2K_KCS_REG_DATA_IN	0x6
+#define LS2K_KCS_REG_CMD	0x8
+
+#define LS2K_KCS_CMD_DATA	0xa
+#define LS2K_KCS_VERSION	0xb
+#define LS2K_KCS_WR_REQ		0xc
+#define LS2K_KCS_WR_ACK		0x10
+
+#define LS2K_KCS_STS_OBF	BIT(0)
+#define LS2K_KCS_STS_IBF	BIT(1)
+#define LS2K_KCS_STS_SMS_ATN	BIT(2)
+#define LS2K_KCS_STS_CMD	BIT(3)
+
+#define LS2K_KCS_DATA_MASK	(LS2K_KCS_STS_OBF | LS2K_KCS_STS_IBF | LS2K_KCS_STS_CMD)
+
+static bool ls2k_registered;
+
+static unsigned char ls2k_mem_inb_v0(const struct si_sm_io *io, unsigned int offset)
+{
+	void __iomem *addr = io->addr;
+	int reg_offset;
+
+	if (offset & BIT(0)) {
+		reg_offset = LS2K_KCS_REG_STS;
+	} else {
+		writeb(readb(addr + LS2K_KCS_REG_STS) & ~LS2K_KCS_STS_OBF, addr + LS2K_KCS_REG_STS);
+		reg_offset = LS2K_KCS_REG_DATA_OUT;
+	}
+
+	return readb(addr + reg_offset);
+}
+
+static unsigned char ls2k_mem_inb_v1(const struct si_sm_io *io, unsigned int offset)
+{
+	void __iomem *addr = io->addr;
+	unsigned char inb = 0, cmd;
+	bool obf, ibf;
+
+	obf = readb(addr + LS2K_KCS_FIFO_OBFH) ^ readb(addr + LS2K_KCS_FIFO_OBFT);
+	ibf = readb(addr + LS2K_KCS_FIFO_IBFH) ^ readb(addr + LS2K_KCS_FIFO_IBFT);
+	cmd = readb(addr + LS2K_KCS_CMD_DATA);
+
+	if (offset & BIT(0)) {
+		inb = readb(addr + LS2K_KCS_REG_STS) & ~LS2K_KCS_DATA_MASK;
+		inb |= FIELD_PREP(LS2K_KCS_STS_OBF, obf)
+		    | FIELD_PREP(LS2K_KCS_STS_IBF, ibf)
+		    | FIELD_PREP(LS2K_KCS_STS_CMD, cmd);
+	} else {
+		inb = readb(addr + LS2K_KCS_REG_DATA_OUT);
+		writeb(readb(addr + LS2K_KCS_FIFO_OBFH), addr + LS2K_KCS_FIFO_OBFT);
+	}
+
+	return inb;
+}
+
+static void ls2k_mem_outb_v0(const struct si_sm_io *io, unsigned int offset,
+			     unsigned char val)
+{
+	void __iomem *addr = io->addr;
+	unsigned char sts = readb(addr + LS2K_KCS_REG_STS);
+	int reg_offset;
+
+	if (sts & LS2K_KCS_STS_IBF)
+		return;
+
+	if (offset & BIT(0)) {
+		reg_offset = LS2K_KCS_REG_CMD;
+		sts |= LS2K_KCS_STS_CMD;
+	} else {
+		reg_offset = LS2K_KCS_REG_DATA_IN;
+		sts &= ~LS2K_KCS_STS_CMD;
+	}
+
+	writew(val, addr + reg_offset);
+	writeb(sts | LS2K_KCS_STS_IBF, addr + LS2K_KCS_REG_STS);
+	writel(readl(addr + LS2K_KCS_WR_REQ) + 1, addr + LS2K_KCS_WR_REQ);
+}
+
+static void ls2k_mem_outb_v1(const struct si_sm_io *io, unsigned int offset,
+			     unsigned char val)
+{
+	void __iomem *addr = io->addr;
+	unsigned char ibfh, ibft;
+	int reg_offset;
+
+	ibfh = readb(addr + LS2K_KCS_FIFO_IBFH);
+	ibft = readb(addr + LS2K_KCS_FIFO_IBFT);
+
+	if (ibfh ^ ibft)
+		return;
+
+	reg_offset = (offset & BIT(0)) ? LS2K_KCS_REG_CMD : LS2K_KCS_REG_DATA_IN;
+	writew(val, addr + reg_offset);
+
+	writeb(offset & BIT(0), addr + LS2K_KCS_CMD_DATA);
+	writeb(!ibft, addr + LS2K_KCS_FIFO_IBFH);
+	writel(readl(addr + LS2K_KCS_WR_REQ) + 1, addr + LS2K_KCS_WR_REQ);
+}
+
+static void ls2k_mem_cleanup(struct si_sm_io *io)
+{
+	if (io->addr)
+		iounmap(io->addr);
+}
+
+static int ipmi_ls2k_mem_setup(struct si_sm_io *io)
+{
+	unsigned char version;
+
+	io->addr = ioremap(io->addr_data, io->regspacing);
+	if (!io->addr)
+		return -EIO;
+
+	version = readb(io->addr + LS2K_KCS_VERSION);
+
+	io->inputb = version ? ls2k_mem_inb_v1 : ls2k_mem_inb_v0;
+	io->outputb = version ? ls2k_mem_outb_v1 : ls2k_mem_outb_v0;
+	io->io_cleanup = ls2k_mem_cleanup;
+
+	return 0;
+}
+
+static int ipmi_ls2k_probe(struct platform_device *pdev)
+{
+	struct si_sm_io io;
+
+	memset(&io, 0, sizeof(io));
+
+	io.si_info	= &ipmi_kcs_si_info;
+	io.io_setup	= ipmi_ls2k_mem_setup;
+	io.addr_data	= pdev->resource[0].start;
+	io.regspacing	= resource_size(&pdev->resource[0]);
+	io.dev		= &pdev->dev;
+
+	dev_dbg(&pdev->dev, "addr 0x%lx, spacing %d.\n", io.addr_data, io.regspacing);
+
+	return ipmi_si_add_smi(&io);
+}
+
+static void ipmi_ls2k_remove(struct platform_device *pdev)
+{
+	ipmi_si_remove_by_dev(&pdev->dev);
+}
+
+struct platform_driver ipmi_ls2k_platform_driver = {
+	.driver = {
+		.name = "ls2k-ipmi-si",
+	},
+	.probe	= ipmi_ls2k_probe,
+	.remove	= ipmi_ls2k_remove,
+};
+
+void ipmi_si_ls2k_init(void)
+{
+	platform_driver_register(&ipmi_ls2k_platform_driver);
+	ls2k_registered = true;
+}
+
+void ipmi_si_ls2k_shutdown(void)
+{
+	if (ls2k_registered)
+		platform_driver_unregister(&ipmi_ls2k_platform_driver);
+}
-- 
2.47.1

Re: [PATCH v4 0/3] LoongArch: Add Loongson-2K BMC support

[Corey Minyard]

On Fri, Jun 13, 2025 at 02:43:38PM +0800, Binbin Zhou wrote:
> Hi all:
> 
> This patch set introduces the Loongson-2K BMC.
> 
> It is a PCIe device present on servers similar to the Loongson-3 CPUs.
> And it is a multifunctional device (MFD), such as display as a sub-function
> of it.

I've asked this before, but I haven't gotten a answer, I don't think.

Is this really a multi-function device?  Is there (or will there be)
another driver that uses the MFD code?

If nothing else is going to use this, then it's really not a
multi-function device and all the code can go into the IPMI directory.
That simplifies maintenance.

If it is a multi-function device, then I want two separate Kconfig
items, one for the MFD and one for the IPMI portion.  That way it's
ready and you don't have to bother about the IPMI portion when
adding the other device.

All else looks good, I think.

-corey

> 
> For IPMI, according to the existing design, we use software simulation to
> implement the KCS interface registers: Stauts/Command/Data_Out/Data_In.
> 
> Also since both host side and BMC side read and write kcs status, we use
> fifo pointer to ensure data consistency.
> 
> For the display, based on simpledrm, the resolution is read from a fixed
> position in the BMC since the hardware does not support auto-detection
> of the resolution. Of course, we will try to support multiple
> resolutions later, through a vbios-like approach.
> 
> Especially, for the BMC reset function, since the display will be
> disconnected when BMC reset, we made a special treatment of re-push.
> 
> Based on this, I will present it in four patches:
> patch-1: BMC device PCI resource allocation.
> patch-2: BMC reset function support
> patch-3: IPMI implementation
> 
> Thanks.
> 
> -------
> V4:
> - Add Reviewed-by tag;
> - Change the order of the patches.
> Patch (1/3):
>   - Fix build warning by lkp: Kconfig tristate -> bool
>     - https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
>  - Update commit message;
>  - Move MFD_LS2K_BMC after MFD_INTEL_M10_BMC_PMCI in Kconfig and
>    Makefile.
> Patch (2/3):
>   - Remove unnecessary newlines;
>   - Rename ls2k_bmc_check_pcie_connected() to
>     ls2k_bmc_pcie_is_connected();
>   - Update comment message.
> Patch (3/3):
>   - Remove unnecessary newlines.
> 
> Link to V3:
> https://lore.kernel.org/all/cover.1748505446.git.zhoubinbin@loongson.cn/
> 
> V3:
> Patch (1/3):
>  - Drop "MFD" in title and comment;
>  - Fromatting code;
>  - Add clearer comments.
> Patch (2/3):
>  - Rebase linux-ipmi/next tree;
>  - Use readx()/writex() to read and write IPMI data instead of structure
>    pointer references;
>  - CONFIG_LOONGARCH -> MFD_LS2K_BMC;
>  - Drop unused output.
> Patch (3/3):
>  - Inline the ls2k_bmc_gpio_reset_handler() function to ls2k_bmc_pdata_initial();
>  - Add clearer comments.
>  - Use proper multi-line commentary as per the Coding Style documentation;
>  - Define all magic numbers.
> 
> Link to V2:
> https://lore.kernel.org/all/cover.1747276047.git.zhoubinbin@loongson.cn/
> 
> V2:
> - Drop ls2kdrm, use simpledrm instead.
> Patch (1/3):
>  - Use DEFINE_RES_MEM_NAMED/MFD_CELL_RES simplified code;
>  - Add resolution fetching due to replacing the original display
>    solution with simpledrm; 
>  - Add aperture_remove_conflicting_devices() to avoid efifb
>    conflict with simpledrm.
> Patch (3/3):
>  - This part of the function, moved from the original ls2kdrm to mfd;
>  - Use set_console to implement the Re-push display function.
> 
> Link to V1:
> https://lore.kernel.org/all/cover.1735550269.git.zhoubinbin@loongson.cn/
> 
> Binbin Zhou (3):
>   mfd: ls2kbmc: Introduce Loongson-2K BMC core driver
>   mfd: ls2kbmc: Add Loongson-2K BMC reset function support
>   ipmi: Add Loongson-2K BMC support
> 
>  drivers/char/ipmi/Makefile       |   1 +
>  drivers/char/ipmi/ipmi_si.h      |   7 +
>  drivers/char/ipmi/ipmi_si_intf.c |   3 +
>  drivers/char/ipmi/ipmi_si_ls2k.c | 189 ++++++++++++
>  drivers/mfd/Kconfig              |  12 +
>  drivers/mfd/Makefile             |   2 +
>  drivers/mfd/ls2kbmc-mfd.c        | 485 +++++++++++++++++++++++++++++++
>  7 files changed, 699 insertions(+)
>  create mode 100644 drivers/char/ipmi/ipmi_si_ls2k.c
>  create mode 100644 drivers/mfd/ls2kbmc-mfd.c
> 
> 
> base-commit: cd2e103d57e5615f9bb027d772f93b9efd567224
> -- 
> 2.47.1
> 

Re: [PATCH v4 0/3] LoongArch: Add Loongson-2K BMC support

[Binbin Zhou]

Hi Corey:

On Sat, Jun 14, 2025 at 8:41 AM Corey Minyard <corey@minyard.net> wrote:
>
> On Fri, Jun 13, 2025 at 02:43:38PM +0800, Binbin Zhou wrote:
> > Hi all:
> >
> > This patch set introduces the Loongson-2K BMC.
> >
> > It is a PCIe device present on servers similar to the Loongson-3 CPUs.
> > And it is a multifunctional device (MFD), such as display as a sub-function
> > of it.
>
> I've asked this before, but I haven't gotten a answer, I don't think.
>
> Is this really a multi-function device?  Is there (or will there be)
> another driver that uses the MFD code?

I am very sorry, I may have overlooked your previous question.

And I also may not have a thorough understanding of multifunction devices.

The Loongson-2K BMC device provides two functions: display and IPMI.
For display, we pass the simplefb_platform_data parameter and register
the simpledrm device, as shown in patch-1.

Therefore, I think this should be considered a multifunction device.

>
> If nothing else is going to use this, then it's really not a
> multi-function device and all the code can go into the IPMI directory.
> That simplifies maintenance.
>
> If it is a multi-function device, then I want two separate Kconfig
> items, one for the MFD and one for the IPMI portion.  That way it's
> ready and you don't have to bother about the IPMI portion when
> adding the other device.
>
> All else looks good, I think.
>
> -corey
>
> >
> > For IPMI, according to the existing design, we use software simulation to
> > implement the KCS interface registers: Stauts/Command/Data_Out/Data_In.
> >
> > Also since both host side and BMC side read and write kcs status, we use
> > fifo pointer to ensure data consistency.
> >
> > For the display, based on simpledrm, the resolution is read from a fixed
> > position in the BMC since the hardware does not support auto-detection
> > of the resolution. Of course, we will try to support multiple
> > resolutions later, through a vbios-like approach.
> >
> > Especially, for the BMC reset function, since the display will be
> > disconnected when BMC reset, we made a special treatment of re-push.
> >
> > Based on this, I will present it in four patches:
> > patch-1: BMC device PCI resource allocation.
> > patch-2: BMC reset function support
> > patch-3: IPMI implementation
> >
> > Thanks.
> >
> > -------
> > V4:
> > - Add Reviewed-by tag;
> > - Change the order of the patches.
> > Patch (1/3):
> >   - Fix build warning by lkp: Kconfig tristate -> bool
> >     - https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
> >  - Update commit message;
> >  - Move MFD_LS2K_BMC after MFD_INTEL_M10_BMC_PMCI in Kconfig and
> >    Makefile.
> > Patch (2/3):
> >   - Remove unnecessary newlines;
> >   - Rename ls2k_bmc_check_pcie_connected() to
> >     ls2k_bmc_pcie_is_connected();
> >   - Update comment message.
> > Patch (3/3):
> >   - Remove unnecessary newlines.
> >
> > Link to V3:
> > https://lore.kernel.org/all/cover.1748505446.git.zhoubinbin@loongson.cn/
> >
> > V3:
> > Patch (1/3):
> >  - Drop "MFD" in title and comment;
> >  - Fromatting code;
> >  - Add clearer comments.
> > Patch (2/3):
> >  - Rebase linux-ipmi/next tree;
> >  - Use readx()/writex() to read and write IPMI data instead of structure
> >    pointer references;
> >  - CONFIG_LOONGARCH -> MFD_LS2K_BMC;
> >  - Drop unused output.
> > Patch (3/3):
> >  - Inline the ls2k_bmc_gpio_reset_handler() function to ls2k_bmc_pdata_initial();
> >  - Add clearer comments.
> >  - Use proper multi-line commentary as per the Coding Style documentation;
> >  - Define all magic numbers.
> >
> > Link to V2:
> > https://lore.kernel.org/all/cover.1747276047.git.zhoubinbin@loongson.cn/
> >
> > V2:
> > - Drop ls2kdrm, use simpledrm instead.
> > Patch (1/3):
> >  - Use DEFINE_RES_MEM_NAMED/MFD_CELL_RES simplified code;
> >  - Add resolution fetching due to replacing the original display
> >    solution with simpledrm;
> >  - Add aperture_remove_conflicting_devices() to avoid efifb
> >    conflict with simpledrm.
> > Patch (3/3):
> >  - This part of the function, moved from the original ls2kdrm to mfd;
> >  - Use set_console to implement the Re-push display function.
> >
> > Link to V1:
> > https://lore.kernel.org/all/cover.1735550269.git.zhoubinbin@loongson.cn/
> >
> > Binbin Zhou (3):
> >   mfd: ls2kbmc: Introduce Loongson-2K BMC core driver
> >   mfd: ls2kbmc: Add Loongson-2K BMC reset function support
> >   ipmi: Add Loongson-2K BMC support
> >
> >  drivers/char/ipmi/Makefile       |   1 +
> >  drivers/char/ipmi/ipmi_si.h      |   7 +
> >  drivers/char/ipmi/ipmi_si_intf.c |   3 +
> >  drivers/char/ipmi/ipmi_si_ls2k.c | 189 ++++++++++++
> >  drivers/mfd/Kconfig              |  12 +
> >  drivers/mfd/Makefile             |   2 +
> >  drivers/mfd/ls2kbmc-mfd.c        | 485 +++++++++++++++++++++++++++++++
> >  7 files changed, 699 insertions(+)
> >  create mode 100644 drivers/char/ipmi/ipmi_si_ls2k.c
> >  create mode 100644 drivers/mfd/ls2kbmc-mfd.c
> >
> >
> > base-commit: cd2e103d57e5615f9bb027d772f93b9efd567224
> > --
> > 2.47.1
> >


-- 
Thanks.
Binbin

Re: [PATCH v4 0/3] LoongArch: Add Loongson-2K BMC support

[Corey Minyard]

On Sat, Jun 14, 2025 at 10:50:37AM +0800, Binbin Zhou wrote:
> Hi Corey:
> 
> On Sat, Jun 14, 2025 at 8:41 AM Corey Minyard <corey@minyard.net> wrote:
> >
> > On Fri, Jun 13, 2025 at 02:43:38PM +0800, Binbin Zhou wrote:
> > > Hi all:
> > >
> > > This patch set introduces the Loongson-2K BMC.
> > >
> > > It is a PCIe device present on servers similar to the Loongson-3 CPUs.
> > > And it is a multifunctional device (MFD), such as display as a sub-function
> > > of it.
> >
> > I've asked this before, but I haven't gotten a answer, I don't think.
> >
> > Is this really a multi-function device?  Is there (or will there be)
> > another driver that uses the MFD code?
> 
> I am very sorry, I may have overlooked your previous question.
> 
> And I also may not have a thorough understanding of multifunction devices.
> 
> The Loongson-2K BMC device provides two functions: display and IPMI.
> For display, we pass the simplefb_platform_data parameter and register
> the simpledrm device, as shown in patch-1.
> 
> Therefore, I think this should be considered a multifunction device.

Ok, that's clear, thank you.

However, that's not really very clear from the patches you have
provided.  Particularly, the "bmc" in the name from patch 1 makes one
think that it's only a bmc.

The "bmc" name is also a little confusing; the devices with a "bmc" in
the name are all the BMC side, but you are doing a host side device.

If you look at most of the other MFDs, they have a "core" section then
various other parts that use the core.  And possibly parts in other
directories for individual functions.  I think you need to do the same
design.  Have a "core" section that both the display and bmc use, then a
separate display and bmc driver.

That way, you can use the display without the IPMI interface, or the
IPMI interface without the display.

I would like to see:

* A core mfd device named ls2k-core.c that has the core functions.
  It would have its own config item (MFD_LS2K) that would be
  selected if either the display or IPMI device is enabled.

* A separate display device in its own file with its own config item.
  This isn't my area, so I'm not sure where this should go.

* The IPMI device in the ipmi directory named ipmi_ls2k.c, again
  with it's own config item (IPMI_LS2K).

Does that make sense?  I don't want to make things too hard, but that's
the way pretty much everything else is done on MFDs.

Thanks,

-corey

> 
> >
> > If nothing else is going to use this, then it's really not a
> > multi-function device and all the code can go into the IPMI directory.
> > That simplifies maintenance.
> >
> > If it is a multi-function device, then I want two separate Kconfig
> > items, one for the MFD and one for the IPMI portion.  That way it's
> > ready and you don't have to bother about the IPMI portion when
> > adding the other device.
> >
> > All else looks good, I think.
> >
> > -corey
> >
> > >
> > > For IPMI, according to the existing design, we use software simulation to
> > > implement the KCS interface registers: Stauts/Command/Data_Out/Data_In.
> > >
> > > Also since both host side and BMC side read and write kcs status, we use
> > > fifo pointer to ensure data consistency.
> > >
> > > For the display, based on simpledrm, the resolution is read from a fixed
> > > position in the BMC since the hardware does not support auto-detection
> > > of the resolution. Of course, we will try to support multiple
> > > resolutions later, through a vbios-like approach.
> > >
> > > Especially, for the BMC reset function, since the display will be
> > > disconnected when BMC reset, we made a special treatment of re-push.
> > >
> > > Based on this, I will present it in four patches:
> > > patch-1: BMC device PCI resource allocation.
> > > patch-2: BMC reset function support
> > > patch-3: IPMI implementation
> > >
> > > Thanks.
> > >
> > > -------
> > > V4:
> > > - Add Reviewed-by tag;
> > > - Change the order of the patches.
> > > Patch (1/3):
> > >   - Fix build warning by lkp: Kconfig tristate -> bool
> > >     - https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
> > >  - Update commit message;
> > >  - Move MFD_LS2K_BMC after MFD_INTEL_M10_BMC_PMCI in Kconfig and
> > >    Makefile.
> > > Patch (2/3):
> > >   - Remove unnecessary newlines;
> > >   - Rename ls2k_bmc_check_pcie_connected() to
> > >     ls2k_bmc_pcie_is_connected();
> > >   - Update comment message.
> > > Patch (3/3):
> > >   - Remove unnecessary newlines.
> > >
> > > Link to V3:
> > > https://lore.kernel.org/all/cover.1748505446.git.zhoubinbin@loongson.cn/
> > >
> > > V3:
> > > Patch (1/3):
> > >  - Drop "MFD" in title and comment;
> > >  - Fromatting code;
> > >  - Add clearer comments.
> > > Patch (2/3):
> > >  - Rebase linux-ipmi/next tree;
> > >  - Use readx()/writex() to read and write IPMI data instead of structure
> > >    pointer references;
> > >  - CONFIG_LOONGARCH -> MFD_LS2K_BMC;
> > >  - Drop unused output.
> > > Patch (3/3):
> > >  - Inline the ls2k_bmc_gpio_reset_handler() function to ls2k_bmc_pdata_initial();
> > >  - Add clearer comments.
> > >  - Use proper multi-line commentary as per the Coding Style documentation;
> > >  - Define all magic numbers.
> > >
> > > Link to V2:
> > > https://lore.kernel.org/all/cover.1747276047.git.zhoubinbin@loongson.cn/
> > >
> > > V2:
> > > - Drop ls2kdrm, use simpledrm instead.
> > > Patch (1/3):
> > >  - Use DEFINE_RES_MEM_NAMED/MFD_CELL_RES simplified code;
> > >  - Add resolution fetching due to replacing the original display
> > >    solution with simpledrm;
> > >  - Add aperture_remove_conflicting_devices() to avoid efifb
> > >    conflict with simpledrm.
> > > Patch (3/3):
> > >  - This part of the function, moved from the original ls2kdrm to mfd;
> > >  - Use set_console to implement the Re-push display function.
> > >
> > > Link to V1:
> > > https://lore.kernel.org/all/cover.1735550269.git.zhoubinbin@loongson.cn/
> > >
> > > Binbin Zhou (3):
> > >   mfd: ls2kbmc: Introduce Loongson-2K BMC core driver
> > >   mfd: ls2kbmc: Add Loongson-2K BMC reset function support
> > >   ipmi: Add Loongson-2K BMC support
> > >
> > >  drivers/char/ipmi/Makefile       |   1 +
> > >  drivers/char/ipmi/ipmi_si.h      |   7 +
> > >  drivers/char/ipmi/ipmi_si_intf.c |   3 +
> > >  drivers/char/ipmi/ipmi_si_ls2k.c | 189 ++++++++++++
> > >  drivers/mfd/Kconfig              |  12 +
> > >  drivers/mfd/Makefile             |   2 +
> > >  drivers/mfd/ls2kbmc-mfd.c        | 485 +++++++++++++++++++++++++++++++
> > >  7 files changed, 699 insertions(+)
> > >  create mode 100644 drivers/char/ipmi/ipmi_si_ls2k.c
> > >  create mode 100644 drivers/mfd/ls2kbmc-mfd.c
> > >
> > >
> > > base-commit: cd2e103d57e5615f9bb027d772f93b9efd567224
> > > --
> > > 2.47.1
> > >
> 
> 
> -- 
> Thanks.
> Binbin

Re: [PATCH v4 0/3] LoongArch: Add Loongson-2K BMC support

[Binbin Zhou]

Hi Corey:

Thanks for your detailed suggestions.

On Sat, Jun 14, 2025 at 11:20 AM Corey Minyard <corey@minyard.net> wrote:
>
> On Sat, Jun 14, 2025 at 10:50:37AM +0800, Binbin Zhou wrote:
> > Hi Corey:
> >
> > On Sat, Jun 14, 2025 at 8:41 AM Corey Minyard <corey@minyard.net> wrote:
> > >
> > > On Fri, Jun 13, 2025 at 02:43:38PM +0800, Binbin Zhou wrote:
> > > > Hi all:
> > > >
> > > > This patch set introduces the Loongson-2K BMC.
> > > >
> > > > It is a PCIe device present on servers similar to the Loongson-3 CPUs.
> > > > And it is a multifunctional device (MFD), such as display as a sub-function
> > > > of it.
> > >
> > > I've asked this before, but I haven't gotten a answer, I don't think.
> > >
> > > Is this really a multi-function device?  Is there (or will there be)
> > > another driver that uses the MFD code?
> >
> > I am very sorry, I may have overlooked your previous question.
> >
> > And I also may not have a thorough understanding of multifunction devices.
> >
> > The Loongson-2K BMC device provides two functions: display and IPMI.
> > For display, we pass the simplefb_platform_data parameter and register
> > the simpledrm device, as shown in patch-1.
> >
> > Therefore, I think this should be considered a multifunction device.
>
> Ok, that's clear, thank you.
>
> However, that's not really very clear from the patches you have
> provided.  Particularly, the "bmc" in the name from patch 1 makes one
> think that it's only a bmc.
>
> The "bmc" name is also a little confusing; the devices with a "bmc" in
> the name are all the BMC side, but you are doing a host side device.
>
> If you look at most of the other MFDs, they have a "core" section then
> various other parts that use the core.  And possibly parts in other
> directories for individual functions.  I think you need to do the same
> design.  Have a "core" section that both the display and bmc use, then a
> separate display and bmc driver.

If it can be reconstructed in this way, it should be clearer.

However, there is a key point in my mind: if the display and IPMI are
separated into two parts, they should at least be able to be probed
separately, but in fact they belong to the same PCI-E device, just
allocated different resource intervals.

static struct pci_device_id ls2k_bmc_devices[] = {
       { PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 0x1a05) },
       { }
};
MODULE_DEVICE_TABLE(pci, ls2k_bmc_devices);

I'm not sure if my understanding is correct?

>
> That way, you can use the display without the IPMI interface, or the
> IPMI interface without the display.
>
> I would like to see:
>
> * A core mfd device named ls2k-core.c that has the core functions.
>   It would have its own config item (MFD_LS2K) that would be
>   selected if either the display or IPMI device is enabled.
>
> * A separate display device in its own file with its own config item.
>   This isn't my area, so I'm not sure where this should go.
>
> * The IPMI device in the ipmi directory named ipmi_ls2k.c, again
>   with it's own config item (IPMI_LS2K).
>
> Does that make sense?  I don't want to make things too hard, but that's
> the way pretty much everything else is done on MFDs.
>
> Thanks,
>
> -corey
>
> >
> > >
> > > If nothing else is going to use this, then it's really not a
> > > multi-function device and all the code can go into the IPMI directory.
> > > That simplifies maintenance.
> > >
> > > If it is a multi-function device, then I want two separate Kconfig
> > > items, one for the MFD and one for the IPMI portion.  That way it's
> > > ready and you don't have to bother about the IPMI portion when
> > > adding the other device.
> > >
> > > All else looks good, I think.
> > >
> > > -corey
> > >
> > > >
> > > > For IPMI, according to the existing design, we use software simulation to
> > > > implement the KCS interface registers: Stauts/Command/Data_Out/Data_In.
> > > >
> > > > Also since both host side and BMC side read and write kcs status, we use
> > > > fifo pointer to ensure data consistency.
> > > >
> > > > For the display, based on simpledrm, the resolution is read from a fixed
> > > > position in the BMC since the hardware does not support auto-detection
> > > > of the resolution. Of course, we will try to support multiple
> > > > resolutions later, through a vbios-like approach.
> > > >
> > > > Especially, for the BMC reset function, since the display will be
> > > > disconnected when BMC reset, we made a special treatment of re-push.
> > > >
> > > > Based on this, I will present it in four patches:
> > > > patch-1: BMC device PCI resource allocation.
> > > > patch-2: BMC reset function support
> > > > patch-3: IPMI implementation
> > > >
> > > > Thanks.
> > > >
> > > > -------
> > > > V4:
> > > > - Add Reviewed-by tag;
> > > > - Change the order of the patches.
> > > > Patch (1/3):
> > > >   - Fix build warning by lkp: Kconfig tristate -> bool
> > > >     - https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
> > > >  - Update commit message;
> > > >  - Move MFD_LS2K_BMC after MFD_INTEL_M10_BMC_PMCI in Kconfig and
> > > >    Makefile.
> > > > Patch (2/3):
> > > >   - Remove unnecessary newlines;
> > > >   - Rename ls2k_bmc_check_pcie_connected() to
> > > >     ls2k_bmc_pcie_is_connected();
> > > >   - Update comment message.
> > > > Patch (3/3):
> > > >   - Remove unnecessary newlines.
> > > >
> > > > Link to V3:
> > > > https://lore.kernel.org/all/cover.1748505446.git.zhoubinbin@loongson.cn/
> > > >
> > > > V3:
> > > > Patch (1/3):
> > > >  - Drop "MFD" in title and comment;
> > > >  - Fromatting code;
> > > >  - Add clearer comments.
> > > > Patch (2/3):
> > > >  - Rebase linux-ipmi/next tree;
> > > >  - Use readx()/writex() to read and write IPMI data instead of structure
> > > >    pointer references;
> > > >  - CONFIG_LOONGARCH -> MFD_LS2K_BMC;
> > > >  - Drop unused output.
> > > > Patch (3/3):
> > > >  - Inline the ls2k_bmc_gpio_reset_handler() function to ls2k_bmc_pdata_initial();
> > > >  - Add clearer comments.
> > > >  - Use proper multi-line commentary as per the Coding Style documentation;
> > > >  - Define all magic numbers.
> > > >
> > > > Link to V2:
> > > > https://lore.kernel.org/all/cover.1747276047.git.zhoubinbin@loongson.cn/
> > > >
> > > > V2:
> > > > - Drop ls2kdrm, use simpledrm instead.
> > > > Patch (1/3):
> > > >  - Use DEFINE_RES_MEM_NAMED/MFD_CELL_RES simplified code;
> > > >  - Add resolution fetching due to replacing the original display
> > > >    solution with simpledrm;
> > > >  - Add aperture_remove_conflicting_devices() to avoid efifb
> > > >    conflict with simpledrm.
> > > > Patch (3/3):
> > > >  - This part of the function, moved from the original ls2kdrm to mfd;
> > > >  - Use set_console to implement the Re-push display function.
> > > >
> > > > Link to V1:
> > > > https://lore.kernel.org/all/cover.1735550269.git.zhoubinbin@loongson.cn/
> > > >
> > > > Binbin Zhou (3):
> > > >   mfd: ls2kbmc: Introduce Loongson-2K BMC core driver
> > > >   mfd: ls2kbmc: Add Loongson-2K BMC reset function support
> > > >   ipmi: Add Loongson-2K BMC support
> > > >
> > > >  drivers/char/ipmi/Makefile       |   1 +
> > > >  drivers/char/ipmi/ipmi_si.h      |   7 +
> > > >  drivers/char/ipmi/ipmi_si_intf.c |   3 +
> > > >  drivers/char/ipmi/ipmi_si_ls2k.c | 189 ++++++++++++
> > > >  drivers/mfd/Kconfig              |  12 +
> > > >  drivers/mfd/Makefile             |   2 +
> > > >  drivers/mfd/ls2kbmc-mfd.c        | 485 +++++++++++++++++++++++++++++++
> > > >  7 files changed, 699 insertions(+)
> > > >  create mode 100644 drivers/char/ipmi/ipmi_si_ls2k.c
> > > >  create mode 100644 drivers/mfd/ls2kbmc-mfd.c
> > > >
> > > >
> > > > base-commit: cd2e103d57e5615f9bb027d772f93b9efd567224
> > > > --
> > > > 2.47.1
> > > >
> >
> >
> > --
> > Thanks.
> > Binbin

-- 
Thanks.
Binbin

Re: [PATCH v4 0/3] LoongArch: Add Loongson-2K BMC support

[Corey Minyard]

On Sat, Jun 14, 2025 at 01:25:17PM +0800, Binbin Zhou wrote:
> Hi Corey:
> 
> Thanks for your detailed suggestions.
> 
> On Sat, Jun 14, 2025 at 11:20 AM Corey Minyard <corey@minyard.net> wrote:
> >
> > On Sat, Jun 14, 2025 at 10:50:37AM +0800, Binbin Zhou wrote:
> > > Hi Corey:
> > >
> > > On Sat, Jun 14, 2025 at 8:41 AM Corey Minyard <corey@minyard.net> wrote:
> > > >
> > > > On Fri, Jun 13, 2025 at 02:43:38PM +0800, Binbin Zhou wrote:
> > > > > Hi all:
> > > > >
> > > > > This patch set introduces the Loongson-2K BMC.
> > > > >
> > > > > It is a PCIe device present on servers similar to the Loongson-3 CPUs.
> > > > > And it is a multifunctional device (MFD), such as display as a sub-function
> > > > > of it.
> > > >
> > > > I've asked this before, but I haven't gotten a answer, I don't think.
> > > >
> > > > Is this really a multi-function device?  Is there (or will there be)
> > > > another driver that uses the MFD code?
> > >
> > > I am very sorry, I may have overlooked your previous question.
> > >
> > > And I also may not have a thorough understanding of multifunction devices.
> > >
> > > The Loongson-2K BMC device provides two functions: display and IPMI.
> > > For display, we pass the simplefb_platform_data parameter and register
> > > the simpledrm device, as shown in patch-1.
> > >
> > > Therefore, I think this should be considered a multifunction device.
> >
> > Ok, that's clear, thank you.
> >
> > However, that's not really very clear from the patches you have
> > provided.  Particularly, the "bmc" in the name from patch 1 makes one
> > think that it's only a bmc.
> >
> > The "bmc" name is also a little confusing; the devices with a "bmc" in
> > the name are all the BMC side, but you are doing a host side device.
> >
> > If you look at most of the other MFDs, they have a "core" section then
> > various other parts that use the core.  And possibly parts in other
> > directories for individual functions.  I think you need to do the same
> > design.  Have a "core" section that both the display and bmc use, then a
> > separate display and bmc driver.
> 
> If it can be reconstructed in this way, it should be clearer.
> 
> However, there is a key point in my mind: if the display and IPMI are
> separated into two parts, they should at least be able to be probed
> separately, but in fact they belong to the same PCI-E device, just
> allocated different resource intervals.
> 
> static struct pci_device_id ls2k_bmc_devices[] = {
>        { PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 0x1a05) },
>        { }
> };
> MODULE_DEVICE_TABLE(pci, ls2k_bmc_devices);
> 
> I'm not sure if my understanding is correct?

You are already doing this, it appears.  I spent a little time to learn
how this works.  You are using the standard frame buffer driver, so no
special driver is required there (per earlier discussions).  And you are
registering it all as an MFD device, so the display buffer and IPMI
interface will pick it up there.

So from a design point of view this all looks good.

The IPMI interface needs to be separately selectable from the main mfd
device in the Kconfigs.  Add an IPMI_LS2K config in the IPMI section
that enables the IPMI interface and selects MFD_LS2K_BMC.  And both
configs need to be tristate, not bool, so they can be modules.

I don't know if you want to make the display part so it can be enabled
separately, I'm not sure how you would do that.  But that's not my
concern, really.

Thanks,

-corey

> 
> >
> > That way, you can use the display without the IPMI interface, or the
> > IPMI interface without the display.
> >
> > I would like to see:
> >
> > * A core mfd device named ls2k-core.c that has the core functions.
> >   It would have its own config item (MFD_LS2K) that would be
> >   selected if either the display or IPMI device is enabled.
> >
> > * A separate display device in its own file with its own config item.
> >   This isn't my area, so I'm not sure where this should go.
> >
> > * The IPMI device in the ipmi directory named ipmi_ls2k.c, again
> >   with it's own config item (IPMI_LS2K).
> >
> > Does that make sense?  I don't want to make things too hard, but that's
> > the way pretty much everything else is done on MFDs.
> >
> > Thanks,
> >
> > -corey
> >
> > >
> > > >
> > > > If nothing else is going to use this, then it's really not a
> > > > multi-function device and all the code can go into the IPMI directory.
> > > > That simplifies maintenance.
> > > >
> > > > If it is a multi-function device, then I want two separate Kconfig
> > > > items, one for the MFD and one for the IPMI portion.  That way it's
> > > > ready and you don't have to bother about the IPMI portion when
> > > > adding the other device.
> > > >
> > > > All else looks good, I think.
> > > >
> > > > -corey
> > > >
> > > > >
> > > > > For IPMI, according to the existing design, we use software simulation to
> > > > > implement the KCS interface registers: Stauts/Command/Data_Out/Data_In.
> > > > >
> > > > > Also since both host side and BMC side read and write kcs status, we use
> > > > > fifo pointer to ensure data consistency.
> > > > >
> > > > > For the display, based on simpledrm, the resolution is read from a fixed
> > > > > position in the BMC since the hardware does not support auto-detection
> > > > > of the resolution. Of course, we will try to support multiple
> > > > > resolutions later, through a vbios-like approach.
> > > > >
> > > > > Especially, for the BMC reset function, since the display will be
> > > > > disconnected when BMC reset, we made a special treatment of re-push.
> > > > >
> > > > > Based on this, I will present it in four patches:
> > > > > patch-1: BMC device PCI resource allocation.
> > > > > patch-2: BMC reset function support
> > > > > patch-3: IPMI implementation
> > > > >
> > > > > Thanks.
> > > > >
> > > > > -------
> > > > > V4:
> > > > > - Add Reviewed-by tag;
> > > > > - Change the order of the patches.
> > > > > Patch (1/3):
> > > > >   - Fix build warning by lkp: Kconfig tristate -> bool
> > > > >     - https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
> > > > >  - Update commit message;
> > > > >  - Move MFD_LS2K_BMC after MFD_INTEL_M10_BMC_PMCI in Kconfig and
> > > > >    Makefile.
> > > > > Patch (2/3):
> > > > >   - Remove unnecessary newlines;
> > > > >   - Rename ls2k_bmc_check_pcie_connected() to
> > > > >     ls2k_bmc_pcie_is_connected();
> > > > >   - Update comment message.
> > > > > Patch (3/3):
> > > > >   - Remove unnecessary newlines.
> > > > >
> > > > > Link to V3:
> > > > > https://lore.kernel.org/all/cover.1748505446.git.zhoubinbin@loongson.cn/
> > > > >
> > > > > V3:
> > > > > Patch (1/3):
> > > > >  - Drop "MFD" in title and comment;
> > > > >  - Fromatting code;
> > > > >  - Add clearer comments.
> > > > > Patch (2/3):
> > > > >  - Rebase linux-ipmi/next tree;
> > > > >  - Use readx()/writex() to read and write IPMI data instead of structure
> > > > >    pointer references;
> > > > >  - CONFIG_LOONGARCH -> MFD_LS2K_BMC;
> > > > >  - Drop unused output.
> > > > > Patch (3/3):
> > > > >  - Inline the ls2k_bmc_gpio_reset_handler() function to ls2k_bmc_pdata_initial();
> > > > >  - Add clearer comments.
> > > > >  - Use proper multi-line commentary as per the Coding Style documentation;
> > > > >  - Define all magic numbers.
> > > > >
> > > > > Link to V2:
> > > > > https://lore.kernel.org/all/cover.1747276047.git.zhoubinbin@loongson.cn/
> > > > >
> > > > > V2:
> > > > > - Drop ls2kdrm, use simpledrm instead.
> > > > > Patch (1/3):
> > > > >  - Use DEFINE_RES_MEM_NAMED/MFD_CELL_RES simplified code;
> > > > >  - Add resolution fetching due to replacing the original display
> > > > >    solution with simpledrm;
> > > > >  - Add aperture_remove_conflicting_devices() to avoid efifb
> > > > >    conflict with simpledrm.
> > > > > Patch (3/3):
> > > > >  - This part of the function, moved from the original ls2kdrm to mfd;
> > > > >  - Use set_console to implement the Re-push display function.
> > > > >
> > > > > Link to V1:
> > > > > https://lore.kernel.org/all/cover.1735550269.git.zhoubinbin@loongson.cn/
> > > > >
> > > > > Binbin Zhou (3):
> > > > >   mfd: ls2kbmc: Introduce Loongson-2K BMC core driver
> > > > >   mfd: ls2kbmc: Add Loongson-2K BMC reset function support
> > > > >   ipmi: Add Loongson-2K BMC support
> > > > >
> > > > >  drivers/char/ipmi/Makefile       |   1 +
> > > > >  drivers/char/ipmi/ipmi_si.h      |   7 +
> > > > >  drivers/char/ipmi/ipmi_si_intf.c |   3 +
> > > > >  drivers/char/ipmi/ipmi_si_ls2k.c | 189 ++++++++++++
> > > > >  drivers/mfd/Kconfig              |  12 +
> > > > >  drivers/mfd/Makefile             |   2 +
> > > > >  drivers/mfd/ls2kbmc-mfd.c        | 485 +++++++++++++++++++++++++++++++
> > > > >  7 files changed, 699 insertions(+)
> > > > >  create mode 100644 drivers/char/ipmi/ipmi_si_ls2k.c
> > > > >  create mode 100644 drivers/mfd/ls2kbmc-mfd.c
> > > > >
> > > > >
> > > > > base-commit: cd2e103d57e5615f9bb027d772f93b9efd567224
> > > > > --
> > > > > 2.47.1
> > > > >
> > >
> > >
> > > --
> > > Thanks.
> > > Binbin
> 
> -- 
> Thanks.
> Binbin

Re: [PATCH v4 0/3] LoongArch: Add Loongson-2K BMC support

[Binbin Zhou]

Hi Corey:

Thanks  for your detailed review.

On Sat, Jun 14, 2025 at 9:59 PM Corey Minyard <corey@minyard.net> wrote:
>
> On Sat, Jun 14, 2025 at 01:25:17PM +0800, Binbin Zhou wrote:
> > Hi Corey:
> >
> > Thanks for your detailed suggestions.
> >
> > On Sat, Jun 14, 2025 at 11:20 AM Corey Minyard <corey@minyard.net> wrote:
> > >
> > > On Sat, Jun 14, 2025 at 10:50:37AM +0800, Binbin Zhou wrote:
> > > > Hi Corey:
> > > >
> > > > On Sat, Jun 14, 2025 at 8:41 AM Corey Minyard <corey@minyard.net> wrote:
> > > > >
> > > > > On Fri, Jun 13, 2025 at 02:43:38PM +0800, Binbin Zhou wrote:
> > > > > > Hi all:
> > > > > >
> > > > > > This patch set introduces the Loongson-2K BMC.
> > > > > >
> > > > > > It is a PCIe device present on servers similar to the Loongson-3 CPUs.
> > > > > > And it is a multifunctional device (MFD), such as display as a sub-function
> > > > > > of it.
> > > > >
> > > > > I've asked this before, but I haven't gotten a answer, I don't think.
> > > > >
> > > > > Is this really a multi-function device?  Is there (or will there be)
> > > > > another driver that uses the MFD code?
> > > >
> > > > I am very sorry, I may have overlooked your previous question.
> > > >
> > > > And I also may not have a thorough understanding of multifunction devices.
> > > >
> > > > The Loongson-2K BMC device provides two functions: display and IPMI.
> > > > For display, we pass the simplefb_platform_data parameter and register
> > > > the simpledrm device, as shown in patch-1.
> > > >
> > > > Therefore, I think this should be considered a multifunction device.
> > >
> > > Ok, that's clear, thank you.
> > >
> > > However, that's not really very clear from the patches you have
> > > provided.  Particularly, the "bmc" in the name from patch 1 makes one
> > > think that it's only a bmc.
> > >
> > > The "bmc" name is also a little confusing; the devices with a "bmc" in
> > > the name are all the BMC side, but you are doing a host side device.
> > >
> > > If you look at most of the other MFDs, they have a "core" section then
> > > various other parts that use the core.  And possibly parts in other
> > > directories for individual functions.  I think you need to do the same
> > > design.  Have a "core" section that both the display and bmc use, then a
> > > separate display and bmc driver.
> >
> > If it can be reconstructed in this way, it should be clearer.
> >
> > However, there is a key point in my mind: if the display and IPMI are
> > separated into two parts, they should at least be able to be probed
> > separately, but in fact they belong to the same PCI-E device, just
> > allocated different resource intervals.
> >
> > static struct pci_device_id ls2k_bmc_devices[] = {
> >        { PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 0x1a05) },
> >        { }
> > };
> > MODULE_DEVICE_TABLE(pci, ls2k_bmc_devices);
> >
> > I'm not sure if my understanding is correct?
>
> You are already doing this, it appears.  I spent a little time to learn
> how this works.  You are using the standard frame buffer driver, so no
> special driver is required there (per earlier discussions).  And you are
> registering it all as an MFD device, so the display buffer and IPMI
> interface will pick it up there.
>
> So from a design point of view this all looks good.
>
> The IPMI interface needs to be separately selectable from the main mfd
> device in the Kconfigs.  Add an IPMI_LS2K config in the IPMI section
> that enables the IPMI interface and selects MFD_LS2K_BMC.  And both
> configs need to be tristate, not bool, so they can be modules.

I tried rewriting Kconfig as follows:

IPMI Kconfig:

config IPMI_LS2K
       bool 'Loongson-2K IPMI interface'
       depends on LOONGARCH
       select MFD_LS2K_BMC_CORE
       help
         Provides a driver for Loongson-2K IPMI interfaces.

MFD Kconfig:

config MFD_LS2K_BMC_CORE
        bool "Loongson-2K Board Management Controller Support"
        select MFD_CORE


However, `tristate` does not seem to work.
On the IPMI side, in order to better reuse code, our driver is not
actually a completely independent driver; it is part of `ipmi_si`.

diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 7fe891783a37..c13d5132fffc 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -2120,6 +2120,8 @@ static int __init init_ipmi_si(void)

        ipmi_si_pci_init();

+       ipmi_si_ls2k_init();
+
        ipmi_si_parisc_init();

        mutex_lock(&smi_infos_lock);
@@ -2334,6 +2335,8 @@ static void cleanup_ipmi_si(void)

        ipmi_si_pci_shutdown();

+       ipmi_si_ls2k_shutdown();
+
        ipmi_si_parisc_shutdown();

        ipmi_si_platform_shutdown();


Therefore, it seems that we can only use `bool` here, otherwise an
error will occur during compilation, as seen in the V3 patchset[1]:

[1]: https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/

>
> I don't know if you want to make the display part so it can be enabled
> separately, I'm not sure how you would do that.  But that's not my
> concern, really.
>
> Thanks,
>
> -corey
>
> >
> > >
> > > That way, you can use the display without the IPMI interface, or the
> > > IPMI interface without the display.
> > >
> > > I would like to see:
> > >
> > > * A core mfd device named ls2k-core.c that has the core functions.
> > >   It would have its own config item (MFD_LS2K) that would be
> > >   selected if either the display or IPMI device is enabled.
> > >
> > > * A separate display device in its own file with its own config item.
> > >   This isn't my area, so I'm not sure where this should go.
> > >
> > > * The IPMI device in the ipmi directory named ipmi_ls2k.c, again
> > >   with it's own config item (IPMI_LS2K).
> > >
> > > Does that make sense?  I don't want to make things too hard, but that's
> > > the way pretty much everything else is done on MFDs.
> > >
> > > Thanks,
> > >
> > > -corey
> > >
> > > >
> > > > >
> > > > > If nothing else is going to use this, then it's really not a
> > > > > multi-function device and all the code can go into the IPMI directory.
> > > > > That simplifies maintenance.
> > > > >
> > > > > If it is a multi-function device, then I want two separate Kconfig
> > > > > items, one for the MFD and one for the IPMI portion.  That way it's
> > > > > ready and you don't have to bother about the IPMI portion when
> > > > > adding the other device.
> > > > >
> > > > > All else looks good, I think.
> > > > >
> > > > > -corey
> > > > >
> > > > > >
> > > > > > For IPMI, according to the existing design, we use software simulation to
> > > > > > implement the KCS interface registers: Stauts/Command/Data_Out/Data_In.
> > > > > >
> > > > > > Also since both host side and BMC side read and write kcs status, we use
> > > > > > fifo pointer to ensure data consistency.
> > > > > >
> > > > > > For the display, based on simpledrm, the resolution is read from a fixed
> > > > > > position in the BMC since the hardware does not support auto-detection
> > > > > > of the resolution. Of course, we will try to support multiple
> > > > > > resolutions later, through a vbios-like approach.
> > > > > >
> > > > > > Especially, for the BMC reset function, since the display will be
> > > > > > disconnected when BMC reset, we made a special treatment of re-push.
> > > > > >
> > > > > > Based on this, I will present it in four patches:
> > > > > > patch-1: BMC device PCI resource allocation.
> > > > > > patch-2: BMC reset function support
> > > > > > patch-3: IPMI implementation
> > > > > >
> > > > > > Thanks.
> > > > > >
> > > > > > -------
> > > > > > V4:
> > > > > > - Add Reviewed-by tag;
> > > > > > - Change the order of the patches.
> > > > > > Patch (1/3):
> > > > > >   - Fix build warning by lkp: Kconfig tristate -> bool
> > > > > >     - https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
> > > > > >  - Update commit message;
> > > > > >  - Move MFD_LS2K_BMC after MFD_INTEL_M10_BMC_PMCI in Kconfig and
> > > > > >    Makefile.
> > > > > > Patch (2/3):
> > > > > >   - Remove unnecessary newlines;
> > > > > >   - Rename ls2k_bmc_check_pcie_connected() to
> > > > > >     ls2k_bmc_pcie_is_connected();
> > > > > >   - Update comment message.
> > > > > > Patch (3/3):
> > > > > >   - Remove unnecessary newlines.
> > > > > >
> > > > > > Link to V3:
> > > > > > https://lore.kernel.org/all/cover.1748505446.git.zhoubinbin@loongson.cn/
> > > > > >
> > > > > > V3:
> > > > > > Patch (1/3):
> > > > > >  - Drop "MFD" in title and comment;
> > > > > >  - Fromatting code;
> > > > > >  - Add clearer comments.
> > > > > > Patch (2/3):
> > > > > >  - Rebase linux-ipmi/next tree;
> > > > > >  - Use readx()/writex() to read and write IPMI data instead of structure
> > > > > >    pointer references;
> > > > > >  - CONFIG_LOONGARCH -> MFD_LS2K_BMC;
> > > > > >  - Drop unused output.
> > > > > > Patch (3/3):
> > > > > >  - Inline the ls2k_bmc_gpio_reset_handler() function to ls2k_bmc_pdata_initial();
> > > > > >  - Add clearer comments.
> > > > > >  - Use proper multi-line commentary as per the Coding Style documentation;
> > > > > >  - Define all magic numbers.
> > > > > >
> > > > > > Link to V2:
> > > > > > https://lore.kernel.org/all/cover.1747276047.git.zhoubinbin@loongson.cn/
> > > > > >
> > > > > > V2:
> > > > > > - Drop ls2kdrm, use simpledrm instead.
> > > > > > Patch (1/3):
> > > > > >  - Use DEFINE_RES_MEM_NAMED/MFD_CELL_RES simplified code;
> > > > > >  - Add resolution fetching due to replacing the original display
> > > > > >    solution with simpledrm;
> > > > > >  - Add aperture_remove_conflicting_devices() to avoid efifb
> > > > > >    conflict with simpledrm.
> > > > > > Patch (3/3):
> > > > > >  - This part of the function, moved from the original ls2kdrm to mfd;
> > > > > >  - Use set_console to implement the Re-push display function.
> > > > > >
> > > > > > Link to V1:
> > > > > > https://lore.kernel.org/all/cover.1735550269.git.zhoubinbin@loongson.cn/
> > > > > >
> > > > > > Binbin Zhou (3):
> > > > > >   mfd: ls2kbmc: Introduce Loongson-2K BMC core driver
> > > > > >   mfd: ls2kbmc: Add Loongson-2K BMC reset function support
> > > > > >   ipmi: Add Loongson-2K BMC support
> > > > > >
> > > > > >  drivers/char/ipmi/Makefile       |   1 +
> > > > > >  drivers/char/ipmi/ipmi_si.h      |   7 +
> > > > > >  drivers/char/ipmi/ipmi_si_intf.c |   3 +
> > > > > >  drivers/char/ipmi/ipmi_si_ls2k.c | 189 ++++++++++++
> > > > > >  drivers/mfd/Kconfig              |  12 +
> > > > > >  drivers/mfd/Makefile             |   2 +
> > > > > >  drivers/mfd/ls2kbmc-mfd.c        | 485 +++++++++++++++++++++++++++++++
> > > > > >  7 files changed, 699 insertions(+)
> > > > > >  create mode 100644 drivers/char/ipmi/ipmi_si_ls2k.c
> > > > > >  create mode 100644 drivers/mfd/ls2kbmc-mfd.c
> > > > > >
> > > > > >
> > > > > > base-commit: cd2e103d57e5615f9bb027d772f93b9efd567224
> > > > > > --
> > > > > > 2.47.1
> > > > > >
> > > >
> > > >
> > > > --
> > > > Thanks.
> > > > Binbin
> >
> > --
> > Thanks.
> > Binbin

-- 
Thanks.
Binbin

Re: [PATCH v4 0/3] LoongArch: Add Loongson-2K BMC support

[Corey Minyard]

On Mon, Jun 16, 2025 at 03:35:56PM +0800, Binbin Zhou wrote:
> Hi Corey:
> 
> Thanks  for your detailed review.
> 
> On Sat, Jun 14, 2025 at 9:59 PM Corey Minyard <corey@minyard.net> wrote:
> >
> > On Sat, Jun 14, 2025 at 01:25:17PM +0800, Binbin Zhou wrote:
> > > Hi Corey:
> > >
> > > Thanks for your detailed suggestions.
> > >
> > > On Sat, Jun 14, 2025 at 11:20 AM Corey Minyard <corey@minyard.net> wrote:
> > > >
> > > > On Sat, Jun 14, 2025 at 10:50:37AM +0800, Binbin Zhou wrote:
> > > > > Hi Corey:
> > > > >
> > > > > On Sat, Jun 14, 2025 at 8:41 AM Corey Minyard <corey@minyard.net> wrote:
> > > > > >
> > > > > > On Fri, Jun 13, 2025 at 02:43:38PM +0800, Binbin Zhou wrote:
> > > > > > > Hi all:
> > > > > > >
> > > > > > > This patch set introduces the Loongson-2K BMC.
> > > > > > >
> > > > > > > It is a PCIe device present on servers similar to the Loongson-3 CPUs.
> > > > > > > And it is a multifunctional device (MFD), such as display as a sub-function
> > > > > > > of it.
> > > > > >
> > > > > > I've asked this before, but I haven't gotten a answer, I don't think.
> > > > > >
> > > > > > Is this really a multi-function device?  Is there (or will there be)
> > > > > > another driver that uses the MFD code?
> > > > >
> > > > > I am very sorry, I may have overlooked your previous question.
> > > > >
> > > > > And I also may not have a thorough understanding of multifunction devices.
> > > > >
> > > > > The Loongson-2K BMC device provides two functions: display and IPMI.
> > > > > For display, we pass the simplefb_platform_data parameter and register
> > > > > the simpledrm device, as shown in patch-1.
> > > > >
> > > > > Therefore, I think this should be considered a multifunction device.
> > > >
> > > > Ok, that's clear, thank you.
> > > >
> > > > However, that's not really very clear from the patches you have
> > > > provided.  Particularly, the "bmc" in the name from patch 1 makes one
> > > > think that it's only a bmc.
> > > >
> > > > The "bmc" name is also a little confusing; the devices with a "bmc" in
> > > > the name are all the BMC side, but you are doing a host side device.
> > > >
> > > > If you look at most of the other MFDs, they have a "core" section then
> > > > various other parts that use the core.  And possibly parts in other
> > > > directories for individual functions.  I think you need to do the same
> > > > design.  Have a "core" section that both the display and bmc use, then a
> > > > separate display and bmc driver.
> > >
> > > If it can be reconstructed in this way, it should be clearer.
> > >
> > > However, there is a key point in my mind: if the display and IPMI are
> > > separated into two parts, they should at least be able to be probed
> > > separately, but in fact they belong to the same PCI-E device, just
> > > allocated different resource intervals.
> > >
> > > static struct pci_device_id ls2k_bmc_devices[] = {
> > >        { PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 0x1a05) },
> > >        { }
> > > };
> > > MODULE_DEVICE_TABLE(pci, ls2k_bmc_devices);
> > >
> > > I'm not sure if my understanding is correct?
> >
> > You are already doing this, it appears.  I spent a little time to learn
> > how this works.  You are using the standard frame buffer driver, so no
> > special driver is required there (per earlier discussions).  And you are
> > registering it all as an MFD device, so the display buffer and IPMI
> > interface will pick it up there.
> >
> > So from a design point of view this all looks good.
> >
> > The IPMI interface needs to be separately selectable from the main mfd
> > device in the Kconfigs.  Add an IPMI_LS2K config in the IPMI section
> > that enables the IPMI interface and selects MFD_LS2K_BMC.  And both
> > configs need to be tristate, not bool, so they can be modules.
> 
> I tried rewriting Kconfig as follows:
> 
> IPMI Kconfig:
> 
> config IPMI_LS2K
>        bool 'Loongson-2K IPMI interface'
>        depends on LOONGARCH
>        select MFD_LS2K_BMC_CORE
>        help
>          Provides a driver for Loongson-2K IPMI interfaces.
> 
> MFD Kconfig:
> 
> config MFD_LS2K_BMC_CORE
>         bool "Loongson-2K Board Management Controller Support"
>         select MFD_CORE
> 
> 
> However, `tristate` does not seem to work.
> On the IPMI side, in order to better reuse code, our driver is not
> actually a completely independent driver; it is part of `ipmi_si`.

Ah, yes, that is true.  The trouble with the above is it will select
MFD_LS2K_BMC_CORE as "y" even if ipmi_si is a module.  And that will
force MFD_CORE to be "y" as well.  At least I think it works that way.
Anyway, that's not terrible, but it would be nice to have the core code
as a module if possible.

Another issue is you don't have help text on MFD_LS2K_BMC_CORE code.
You probably want to mention there that it enables the display on
the BMC.

-corey

> 
> diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
> index 7fe891783a37..c13d5132fffc 100644
> --- a/drivers/char/ipmi/ipmi_si_intf.c
> +++ b/drivers/char/ipmi/ipmi_si_intf.c
> @@ -2120,6 +2120,8 @@ static int __init init_ipmi_si(void)
> 
>         ipmi_si_pci_init();
> 
> +       ipmi_si_ls2k_init();
> +
>         ipmi_si_parisc_init();
> 
>         mutex_lock(&smi_infos_lock);
> @@ -2334,6 +2335,8 @@ static void cleanup_ipmi_si(void)
> 
>         ipmi_si_pci_shutdown();
> 
> +       ipmi_si_ls2k_shutdown();
> +
>         ipmi_si_parisc_shutdown();
> 
>         ipmi_si_platform_shutdown();
> 
> 
> Therefore, it seems that we can only use `bool` here, otherwise an
> error will occur during compilation, as seen in the V3 patchset[1]:
> 
> [1]: https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
> 
> >
> > I don't know if you want to make the display part so it can be enabled
> > separately, I'm not sure how you would do that.  But that's not my
> > concern, really.
> >
> > Thanks,
> >
> > -corey
> >
> > >
> > > >
> > > > That way, you can use the display without the IPMI interface, or the
> > > > IPMI interface without the display.
> > > >
> > > > I would like to see:
> > > >
> > > > * A core mfd device named ls2k-core.c that has the core functions.
> > > >   It would have its own config item (MFD_LS2K) that would be
> > > >   selected if either the display or IPMI device is enabled.
> > > >
> > > > * A separate display device in its own file with its own config item.
> > > >   This isn't my area, so I'm not sure where this should go.
> > > >
> > > > * The IPMI device in the ipmi directory named ipmi_ls2k.c, again
> > > >   with it's own config item (IPMI_LS2K).
> > > >
> > > > Does that make sense?  I don't want to make things too hard, but that's
> > > > the way pretty much everything else is done on MFDs.
> > > >
> > > > Thanks,
> > > >
> > > > -corey
> > > >
> > > > >
> > > > > >
> > > > > > If nothing else is going to use this, then it's really not a
> > > > > > multi-function device and all the code can go into the IPMI directory.
> > > > > > That simplifies maintenance.
> > > > > >
> > > > > > If it is a multi-function device, then I want two separate Kconfig
> > > > > > items, one for the MFD and one for the IPMI portion.  That way it's
> > > > > > ready and you don't have to bother about the IPMI portion when
> > > > > > adding the other device.
> > > > > >
> > > > > > All else looks good, I think.
> > > > > >
> > > > > > -corey
> > > > > >
> > > > > > >
> > > > > > > For IPMI, according to the existing design, we use software simulation to
> > > > > > > implement the KCS interface registers: Stauts/Command/Data_Out/Data_In.
> > > > > > >
> > > > > > > Also since both host side and BMC side read and write kcs status, we use
> > > > > > > fifo pointer to ensure data consistency.
> > > > > > >
> > > > > > > For the display, based on simpledrm, the resolution is read from a fixed
> > > > > > > position in the BMC since the hardware does not support auto-detection
> > > > > > > of the resolution. Of course, we will try to support multiple
> > > > > > > resolutions later, through a vbios-like approach.
> > > > > > >
> > > > > > > Especially, for the BMC reset function, since the display will be
> > > > > > > disconnected when BMC reset, we made a special treatment of re-push.
> > > > > > >
> > > > > > > Based on this, I will present it in four patches:
> > > > > > > patch-1: BMC device PCI resource allocation.
> > > > > > > patch-2: BMC reset function support
> > > > > > > patch-3: IPMI implementation
> > > > > > >
> > > > > > > Thanks.
> > > > > > >
> > > > > > > -------
> > > > > > > V4:
> > > > > > > - Add Reviewed-by tag;
> > > > > > > - Change the order of the patches.
> > > > > > > Patch (1/3):
> > > > > > >   - Fix build warning by lkp: Kconfig tristate -> bool
> > > > > > >     - https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
> > > > > > >  - Update commit message;
> > > > > > >  - Move MFD_LS2K_BMC after MFD_INTEL_M10_BMC_PMCI in Kconfig and
> > > > > > >    Makefile.
> > > > > > > Patch (2/3):
> > > > > > >   - Remove unnecessary newlines;
> > > > > > >   - Rename ls2k_bmc_check_pcie_connected() to
> > > > > > >     ls2k_bmc_pcie_is_connected();
> > > > > > >   - Update comment message.
> > > > > > > Patch (3/3):
> > > > > > >   - Remove unnecessary newlines.
> > > > > > >
> > > > > > > Link to V3:
> > > > > > > https://lore.kernel.org/all/cover.1748505446.git.zhoubinbin@loongson.cn/
> > > > > > >
> > > > > > > V3:
> > > > > > > Patch (1/3):
> > > > > > >  - Drop "MFD" in title and comment;
> > > > > > >  - Fromatting code;
> > > > > > >  - Add clearer comments.
> > > > > > > Patch (2/3):
> > > > > > >  - Rebase linux-ipmi/next tree;
> > > > > > >  - Use readx()/writex() to read and write IPMI data instead of structure
> > > > > > >    pointer references;
> > > > > > >  - CONFIG_LOONGARCH -> MFD_LS2K_BMC;
> > > > > > >  - Drop unused output.
> > > > > > > Patch (3/3):
> > > > > > >  - Inline the ls2k_bmc_gpio_reset_handler() function to ls2k_bmc_pdata_initial();
> > > > > > >  - Add clearer comments.
> > > > > > >  - Use proper multi-line commentary as per the Coding Style documentation;
> > > > > > >  - Define all magic numbers.
> > > > > > >
> > > > > > > Link to V2:
> > > > > > > https://lore.kernel.org/all/cover.1747276047.git.zhoubinbin@loongson.cn/
> > > > > > >
> > > > > > > V2:
> > > > > > > - Drop ls2kdrm, use simpledrm instead.
> > > > > > > Patch (1/3):
> > > > > > >  - Use DEFINE_RES_MEM_NAMED/MFD_CELL_RES simplified code;
> > > > > > >  - Add resolution fetching due to replacing the original display
> > > > > > >    solution with simpledrm;
> > > > > > >  - Add aperture_remove_conflicting_devices() to avoid efifb
> > > > > > >    conflict with simpledrm.
> > > > > > > Patch (3/3):
> > > > > > >  - This part of the function, moved from the original ls2kdrm to mfd;
> > > > > > >  - Use set_console to implement the Re-push display function.
> > > > > > >
> > > > > > > Link to V1:
> > > > > > > https://lore.kernel.org/all/cover.1735550269.git.zhoubinbin@loongson.cn/
> > > > > > >
> > > > > > > Binbin Zhou (3):
> > > > > > >   mfd: ls2kbmc: Introduce Loongson-2K BMC core driver
> > > > > > >   mfd: ls2kbmc: Add Loongson-2K BMC reset function support
> > > > > > >   ipmi: Add Loongson-2K BMC support
> > > > > > >
> > > > > > >  drivers/char/ipmi/Makefile       |   1 +
> > > > > > >  drivers/char/ipmi/ipmi_si.h      |   7 +
> > > > > > >  drivers/char/ipmi/ipmi_si_intf.c |   3 +
> > > > > > >  drivers/char/ipmi/ipmi_si_ls2k.c | 189 ++++++++++++
> > > > > > >  drivers/mfd/Kconfig              |  12 +
> > > > > > >  drivers/mfd/Makefile             |   2 +
> > > > > > >  drivers/mfd/ls2kbmc-mfd.c        | 485 +++++++++++++++++++++++++++++++
> > > > > > >  7 files changed, 699 insertions(+)
> > > > > > >  create mode 100644 drivers/char/ipmi/ipmi_si_ls2k.c
> > > > > > >  create mode 100644 drivers/mfd/ls2kbmc-mfd.c
> > > > > > >
> > > > > > >
> > > > > > > base-commit: cd2e103d57e5615f9bb027d772f93b9efd567224
> > > > > > > --
> > > > > > > 2.47.1
> > > > > > >
> > > > >
> > > > >
> > > > > --
> > > > > Thanks.
> > > > > Binbin
> > >
> > > --
> > > Thanks.
> > > Binbin
> 
> -- 
> Thanks.
> Binbin

Re: [PATCH v4 0/3] LoongArch: Add Loongson-2K BMC support

[Binbin Zhou]

On Mon, Jun 16, 2025 at 9:16 PM Corey Minyard <corey@minyard.net> wrote:
>
> On Mon, Jun 16, 2025 at 03:35:56PM +0800, Binbin Zhou wrote:
> > Hi Corey:
> >
> > Thanks  for your detailed review.
> >
> > On Sat, Jun 14, 2025 at 9:59 PM Corey Minyard <corey@minyard.net> wrote:
> > >
> > > On Sat, Jun 14, 2025 at 01:25:17PM +0800, Binbin Zhou wrote:
> > > > Hi Corey:
> > > >
> > > > Thanks for your detailed suggestions.
> > > >
> > > > On Sat, Jun 14, 2025 at 11:20 AM Corey Minyard <corey@minyard.net> wrote:
> > > > >
> > > > > On Sat, Jun 14, 2025 at 10:50:37AM +0800, Binbin Zhou wrote:
> > > > > > Hi Corey:
> > > > > >
> > > > > > On Sat, Jun 14, 2025 at 8:41 AM Corey Minyard <corey@minyard.net> wrote:
> > > > > > >
> > > > > > > On Fri, Jun 13, 2025 at 02:43:38PM +0800, Binbin Zhou wrote:
> > > > > > > > Hi all:
> > > > > > > >
> > > > > > > > This patch set introduces the Loongson-2K BMC.
> > > > > > > >
> > > > > > > > It is a PCIe device present on servers similar to the Loongson-3 CPUs.
> > > > > > > > And it is a multifunctional device (MFD), such as display as a sub-function
> > > > > > > > of it.
> > > > > > >
> > > > > > > I've asked this before, but I haven't gotten a answer, I don't think.
> > > > > > >
> > > > > > > Is this really a multi-function device?  Is there (or will there be)
> > > > > > > another driver that uses the MFD code?
> > > > > >
> > > > > > I am very sorry, I may have overlooked your previous question.
> > > > > >
> > > > > > And I also may not have a thorough understanding of multifunction devices.
> > > > > >
> > > > > > The Loongson-2K BMC device provides two functions: display and IPMI.
> > > > > > For display, we pass the simplefb_platform_data parameter and register
> > > > > > the simpledrm device, as shown in patch-1.
> > > > > >
> > > > > > Therefore, I think this should be considered a multifunction device.
> > > > >
> > > > > Ok, that's clear, thank you.
> > > > >
> > > > > However, that's not really very clear from the patches you have
> > > > > provided.  Particularly, the "bmc" in the name from patch 1 makes one
> > > > > think that it's only a bmc.
> > > > >
> > > > > The "bmc" name is also a little confusing; the devices with a "bmc" in
> > > > > the name are all the BMC side, but you are doing a host side device.
> > > > >
> > > > > If you look at most of the other MFDs, they have a "core" section then
> > > > > various other parts that use the core.  And possibly parts in other
> > > > > directories for individual functions.  I think you need to do the same
> > > > > design.  Have a "core" section that both the display and bmc use, then a
> > > > > separate display and bmc driver.
> > > >
> > > > If it can be reconstructed in this way, it should be clearer.
> > > >
> > > > However, there is a key point in my mind: if the display and IPMI are
> > > > separated into two parts, they should at least be able to be probed
> > > > separately, but in fact they belong to the same PCI-E device, just
> > > > allocated different resource intervals.
> > > >
> > > > static struct pci_device_id ls2k_bmc_devices[] = {
> > > >        { PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, 0x1a05) },
> > > >        { }
> > > > };
> > > > MODULE_DEVICE_TABLE(pci, ls2k_bmc_devices);
> > > >
> > > > I'm not sure if my understanding is correct?
> > >
> > > You are already doing this, it appears.  I spent a little time to learn
> > > how this works.  You are using the standard frame buffer driver, so no
> > > special driver is required there (per earlier discussions).  And you are
> > > registering it all as an MFD device, so the display buffer and IPMI
> > > interface will pick it up there.
> > >
> > > So from a design point of view this all looks good.
> > >
> > > The IPMI interface needs to be separately selectable from the main mfd
> > > device in the Kconfigs.  Add an IPMI_LS2K config in the IPMI section
> > > that enables the IPMI interface and selects MFD_LS2K_BMC.  And both
> > > configs need to be tristate, not bool, so they can be modules.
> >
> > I tried rewriting Kconfig as follows:
> >
> > IPMI Kconfig:
> >
> > config IPMI_LS2K
> >        bool 'Loongson-2K IPMI interface'
> >        depends on LOONGARCH
> >        select MFD_LS2K_BMC_CORE
> >        help
> >          Provides a driver for Loongson-2K IPMI interfaces.
> >
> > MFD Kconfig:
> >
> > config MFD_LS2K_BMC_CORE
> >         bool "Loongson-2K Board Management Controller Support"
> >         select MFD_CORE
> >
> >
> > However, `tristate` does not seem to work.
> > On the IPMI side, in order to better reuse code, our driver is not
> > actually a completely independent driver; it is part of `ipmi_si`.
>
> Ah, yes, that is true.  The trouble with the above is it will select
> MFD_LS2K_BMC_CORE as "y" even if ipmi_si is a module.  And that will
> force MFD_CORE to be "y" as well.  At least I think it works that way.
> Anyway, that's not terrible, but it would be nice to have the core code
> as a module if possible.
>
> Another issue is you don't have help text on MFD_LS2K_BMC_CORE code.
> You probably want to mention there that it enables the display on
> the BMC.

Of course, I will add some information about BMC in the help text.

Finally, I would like to thanks you again for taking the time to
review my patch. I have benefited greatly from it.
>
> -corey
>
> >
> > diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
> > index 7fe891783a37..c13d5132fffc 100644
> > --- a/drivers/char/ipmi/ipmi_si_intf.c
> > +++ b/drivers/char/ipmi/ipmi_si_intf.c
> > @@ -2120,6 +2120,8 @@ static int __init init_ipmi_si(void)
> >
> >         ipmi_si_pci_init();
> >
> > +       ipmi_si_ls2k_init();
> > +
> >         ipmi_si_parisc_init();
> >
> >         mutex_lock(&smi_infos_lock);
> > @@ -2334,6 +2335,8 @@ static void cleanup_ipmi_si(void)
> >
> >         ipmi_si_pci_shutdown();
> >
> > +       ipmi_si_ls2k_shutdown();
> > +
> >         ipmi_si_parisc_shutdown();
> >
> >         ipmi_si_platform_shutdown();
> >
> >
> > Therefore, it seems that we can only use `bool` here, otherwise an
> > error will occur during compilation, as seen in the V3 patchset[1]:
> >
> > [1]: https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
> >
> > >
> > > I don't know if you want to make the display part so it can be enabled
> > > separately, I'm not sure how you would do that.  But that's not my
> > > concern, really.
> > >
> > > Thanks,
> > >
> > > -corey
> > >
> > > >
> > > > >
> > > > > That way, you can use the display without the IPMI interface, or the
> > > > > IPMI interface without the display.
> > > > >
> > > > > I would like to see:
> > > > >
> > > > > * A core mfd device named ls2k-core.c that has the core functions.
> > > > >   It would have its own config item (MFD_LS2K) that would be
> > > > >   selected if either the display or IPMI device is enabled.
> > > > >
> > > > > * A separate display device in its own file with its own config item.
> > > > >   This isn't my area, so I'm not sure where this should go.
> > > > >
> > > > > * The IPMI device in the ipmi directory named ipmi_ls2k.c, again
> > > > >   with it's own config item (IPMI_LS2K).
> > > > >
> > > > > Does that make sense?  I don't want to make things too hard, but that's
> > > > > the way pretty much everything else is done on MFDs.
> > > > >
> > > > > Thanks,
> > > > >
> > > > > -corey
> > > > >
> > > > > >
> > > > > > >
> > > > > > > If nothing else is going to use this, then it's really not a
> > > > > > > multi-function device and all the code can go into the IPMI directory.
> > > > > > > That simplifies maintenance.
> > > > > > >
> > > > > > > If it is a multi-function device, then I want two separate Kconfig
> > > > > > > items, one for the MFD and one for the IPMI portion.  That way it's
> > > > > > > ready and you don't have to bother about the IPMI portion when
> > > > > > > adding the other device.
> > > > > > >
> > > > > > > All else looks good, I think.
> > > > > > >
> > > > > > > -corey
> > > > > > >
> > > > > > > >
> > > > > > > > For IPMI, according to the existing design, we use software simulation to
> > > > > > > > implement the KCS interface registers: Stauts/Command/Data_Out/Data_In.
> > > > > > > >
> > > > > > > > Also since both host side and BMC side read and write kcs status, we use
> > > > > > > > fifo pointer to ensure data consistency.
> > > > > > > >
> > > > > > > > For the display, based on simpledrm, the resolution is read from a fixed
> > > > > > > > position in the BMC since the hardware does not support auto-detection
> > > > > > > > of the resolution. Of course, we will try to support multiple
> > > > > > > > resolutions later, through a vbios-like approach.
> > > > > > > >
> > > > > > > > Especially, for the BMC reset function, since the display will be
> > > > > > > > disconnected when BMC reset, we made a special treatment of re-push.
> > > > > > > >
> > > > > > > > Based on this, I will present it in four patches:
> > > > > > > > patch-1: BMC device PCI resource allocation.
> > > > > > > > patch-2: BMC reset function support
> > > > > > > > patch-3: IPMI implementation
> > > > > > > >
> > > > > > > > Thanks.
> > > > > > > >
> > > > > > > > -------
> > > > > > > > V4:
> > > > > > > > - Add Reviewed-by tag;
> > > > > > > > - Change the order of the patches.
> > > > > > > > Patch (1/3):
> > > > > > > >   - Fix build warning by lkp: Kconfig tristate -> bool
> > > > > > > >     - https://lore.kernel.org/all/202505312022.QmFmGE1F-lkp@intel.com/
> > > > > > > >  - Update commit message;
> > > > > > > >  - Move MFD_LS2K_BMC after MFD_INTEL_M10_BMC_PMCI in Kconfig and
> > > > > > > >    Makefile.
> > > > > > > > Patch (2/3):
> > > > > > > >   - Remove unnecessary newlines;
> > > > > > > >   - Rename ls2k_bmc_check_pcie_connected() to
> > > > > > > >     ls2k_bmc_pcie_is_connected();
> > > > > > > >   - Update comment message.
> > > > > > > > Patch (3/3):
> > > > > > > >   - Remove unnecessary newlines.
> > > > > > > >
> > > > > > > > Link to V3:
> > > > > > > > https://lore.kernel.org/all/cover.1748505446.git.zhoubinbin@loongson.cn/
> > > > > > > >
> > > > > > > > V3:
> > > > > > > > Patch (1/3):
> > > > > > > >  - Drop "MFD" in title and comment;
> > > > > > > >  - Fromatting code;
> > > > > > > >  - Add clearer comments.
> > > > > > > > Patch (2/3):
> > > > > > > >  - Rebase linux-ipmi/next tree;
> > > > > > > >  - Use readx()/writex() to read and write IPMI data instead of structure
> > > > > > > >    pointer references;
> > > > > > > >  - CONFIG_LOONGARCH -> MFD_LS2K_BMC;
> > > > > > > >  - Drop unused output.
> > > > > > > > Patch (3/3):
> > > > > > > >  - Inline the ls2k_bmc_gpio_reset_handler() function to ls2k_bmc_pdata_initial();
> > > > > > > >  - Add clearer comments.
> > > > > > > >  - Use proper multi-line commentary as per the Coding Style documentation;
> > > > > > > >  - Define all magic numbers.
> > > > > > > >
> > > > > > > > Link to V2:
> > > > > > > > https://lore.kernel.org/all/cover.1747276047.git.zhoubinbin@loongson.cn/
> > > > > > > >
> > > > > > > > V2:
> > > > > > > > - Drop ls2kdrm, use simpledrm instead.
> > > > > > > > Patch (1/3):
> > > > > > > >  - Use DEFINE_RES_MEM_NAMED/MFD_CELL_RES simplified code;
> > > > > > > >  - Add resolution fetching due to replacing the original display
> > > > > > > >    solution with simpledrm;
> > > > > > > >  - Add aperture_remove_conflicting_devices() to avoid efifb
> > > > > > > >    conflict with simpledrm.
> > > > > > > > Patch (3/3):
> > > > > > > >  - This part of the function, moved from the original ls2kdrm to mfd;
> > > > > > > >  - Use set_console to implement the Re-push display function.
> > > > > > > >
> > > > > > > > Link to V1:
> > > > > > > > https://lore.kernel.org/all/cover.1735550269.git.zhoubinbin@loongson.cn/
> > > > > > > >
> > > > > > > > Binbin Zhou (3):
> > > > > > > >   mfd: ls2kbmc: Introduce Loongson-2K BMC core driver
> > > > > > > >   mfd: ls2kbmc: Add Loongson-2K BMC reset function support
> > > > > > > >   ipmi: Add Loongson-2K BMC support
> > > > > > > >
> > > > > > > >  drivers/char/ipmi/Makefile       |   1 +
> > > > > > > >  drivers/char/ipmi/ipmi_si.h      |   7 +
> > > > > > > >  drivers/char/ipmi/ipmi_si_intf.c |   3 +
> > > > > > > >  drivers/char/ipmi/ipmi_si_ls2k.c | 189 ++++++++++++
> > > > > > > >  drivers/mfd/Kconfig              |  12 +
> > > > > > > >  drivers/mfd/Makefile             |   2 +
> > > > > > > >  drivers/mfd/ls2kbmc-mfd.c        | 485 +++++++++++++++++++++++++++++++
> > > > > > > >  7 files changed, 699 insertions(+)
> > > > > > > >  create mode 100644 drivers/char/ipmi/ipmi_si_ls2k.c
> > > > > > > >  create mode 100644 drivers/mfd/ls2kbmc-mfd.c
> > > > > > > >
> > > > > > > >
> > > > > > > > base-commit: cd2e103d57e5615f9bb027d772f93b9efd567224
> > > > > > > > --
> > > > > > > > 2.47.1
> > > > > > > >
> > > > > >
> > > > > >
> > > > > > --
> > > > > > Thanks.
> > > > > > Binbin
> > > >
> > > > --
> > > > Thanks.
> > > > Binbin
> >
> > --
> > Thanks.
> > Binbin

-- 
Thanks.
Binbin