[PATCH v2 1/3] mfd: ls2kbmc: Introduce Loongson-2K BMC MFD Core driver

[Binbin Zhou <zhoubinbin@loongson.cn>]

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-3C6000 CPUs. It supports multiple sub-devices like DRM.

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       |  13 ++++
 drivers/mfd/Makefile      |   2 +
 drivers/mfd/ls2kbmc-mfd.c | 156 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 171 insertions(+)
 create mode 100644 drivers/mfd/ls2kbmc-mfd.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 22b936310039..04e40085441d 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -2422,5 +2422,18 @@ config MFD_UPBOARD_FPGA
 	  To compile this driver as a module, choose M here: the module will be
 	  called upboard-fpga.
 
+config MFD_LS2K_BMC
+	tristate "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.
+
 endmenu
 endif
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 948cbdf42a18..18960ea13b64 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -290,3 +290,5 @@ obj-$(CONFIG_MFD_RSMU_I2C)	+= rsmu_i2c.o rsmu_core.o
 obj-$(CONFIG_MFD_RSMU_SPI)	+= rsmu_spi.o rsmu_core.o
 
 obj-$(CONFIG_MFD_UPBOARD_FPGA)	+= upboard-fpga.o
+
+obj-$(CONFIG_MFD_LS2K_BMC)	+= ls2kbmc-mfd.o
diff --git a/drivers/mfd/ls2kbmc-mfd.c b/drivers/mfd/ls2kbmc-mfd.c
new file mode 100644
index 000000000000..b309f6132c24
--- /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) MFD Core Driver.
+ *
+ * Copyright (C) 2024 Loongson Technology Corporation Limited.
+ *
+ * Originally written by Chong Qiao <qiaochong@loongson.cn>
+ * Rewritten for mainline by 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>
+
+#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-2K0500 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_get_video_mode(struct pci_dev *pdev, struct simplefb_platform_data *pd)
+{
+	char *mode;
+	int depth, ret;
+
+	/* The pci mem bar last 16M is used to store the string. */
+	mode = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M, SZ_16M);
+	if (!mode)
+		return -ENOMEM;
+
+	/* env at last 16M's beginning, first env is "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)
+{
+	int ret = 0;
+	resource_size_t base;
+	struct simplefb_platform_data pd;
+
+	ret = pci_enable_device(dev);
+	if (ret)
+		return ret;
+
+	ret = ls2k_bmc_get_video_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, "Remove firmware framebuffers failed: %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