[PATCH v2 3/3] mfd: intel-m10-bmc: add Max10 BMC chip support for Intel FPGA PAC

[Xu Yilun <yilun.xu@intel.com>]

This patch implements the basic functions of the BMC chip for some Intel
FPGA PCIe Acceleration Cards (PAC). The BMC is implemented using the
intel max10 CPLD.

This BMC chip is connected to FPGA by a SPI bus. To provide reliable
register access from FPGA, an Avalon Memory-Mapped (Avmm) transaction
protocol over the SPI bus is used between host and slave.

This driver implements the basic register access using the
regmap-spi-avmm. The mfd cells array is empty now as a placeholder.

Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Signed-off-by: Tom Rix <trix@redhat.com>
---
v2: Split out the regmap-spi-avmm part.
    Rename the file intel-m10-bmc-main.c to intel-m10-bmc.c, cause
     there is only one source file left for this module now.
---
 .../ABI/testing/sysfs-driver-intel-m10-bmc         |  15 ++
 drivers/mfd/Kconfig                                |  13 ++
 drivers/mfd/Makefile                               |   2 +
 drivers/mfd/intel-m10-bmc.c                        | 174 +++++++++++++++++++++
 include/linux/mfd/intel-m10-bmc.h                  |  57 +++++++
 5 files changed, 261 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-intel-m10-bmc
 create mode 100644 drivers/mfd/intel-m10-bmc.c
 create mode 100644 include/linux/mfd/intel-m10-bmc.h

diff --git a/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc
new file mode 100644
index 0000000..54cf5bc
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc
@@ -0,0 +1,15 @@
+What:		/sys/bus/spi/devices/.../bmc_version
+Date:		June 2020
+KernelVersion:	5.9
+Contact:	Xu Yilun <yilun.xu@intel.com>
+Description:	Read only. Returns the hardware build version of Intel
+		MAX10 BMC chip.
+		Format: "0x%x".
+
+What:		/sys/bus/spi/devices/.../bmcfw_version
+Date:		June 2020
+KernelVersion:	5.9
+Contact:	Xu Yilun <yilun.xu@intel.com>
+Description:	Read only. Returns the firmware version of Intel MAX10
+		BMC chip.
+		Format: "0x%x".
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index d13bb0a..42252c8 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -2130,5 +2130,18 @@ config SGI_MFD_IOC3
 	  If you have an SGI Origin, Octane, or a PCI IOC3 card,
 	  then say Y. Otherwise say N.
 
+config MFD_INTEL_M10_BMC
+	tristate "Intel MAX10 board management controller"
+	depends on SPI_MASTER
+	select REGMAP_SPI_AVMM
+	select MFD_CORE
+	help
+	  Support for the Intel MAX10 board management controller using the
+	  SPI interface.
+
+	  This driver provides common support for accessing the device,
+	  additional drivers must be enabled in order to use the functionality
+	  of the device.
+
 endmenu
 endif
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 1c8d6be..149d7d1 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -265,3 +265,5 @@ obj-$(CONFIG_MFD_STMFX) 	+= stmfx.o
 obj-$(CONFIG_MFD_KHADAS_MCU) 	+= khadas-mcu.o
 
 obj-$(CONFIG_SGI_MFD_IOC3)	+= ioc3.o
+
+obj-$(CONFIG_MFD_INTEL_M10_BMC)   += intel-m10-bmc.o
diff --git a/drivers/mfd/intel-m10-bmc.c b/drivers/mfd/intel-m10-bmc.c
new file mode 100644
index 0000000..0d5e5d6
--- /dev/null
+++ b/drivers/mfd/intel-m10-bmc.c
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Intel Max10 Board Management Controller chip Driver
+ *
+ * Copyright (C) 2018-2020 Intel Corporation. All rights reserved.
+ *
+ */
+#include <linux/bitfield.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+#include <linux/module.h>
+#include <linux/mfd/core.h>
+#include <linux/init.h>
+#include <linux/spi/spi.h>
+#include <linux/mfd/intel-m10-bmc.h>
+
+enum m10bmc_type {
+	M10_N3000,
+};
+
+static struct mfd_cell m10bmc_pacn3000_subdevs[] = {};
+
+static struct regmap_config intel_m10bmc_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+	.max_register = M10BMC_MEM_END,
+};
+
+static ssize_t bmc_version_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct intel_m10bmc *m10bmc = dev_get_drvdata(dev);
+	unsigned int val;
+	int ret;
+
+	ret = m10bmc_sys_read(m10bmc, M10BMC_BUILD_VER, &val);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "0x%x\n", val);
+}
+static DEVICE_ATTR_RO(bmc_version);
+
+static ssize_t bmcfw_version_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct intel_m10bmc *max10 = dev_get_drvdata(dev);
+	unsigned int val;
+	int ret;
+
+	ret = m10bmc_sys_read(max10, NIOS2_FW_VERSION, &val);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "0x%x\n", val);
+}
+static DEVICE_ATTR_RO(bmcfw_version);
+
+static struct attribute *m10bmc_attrs[] = {
+	&dev_attr_bmc_version.attr,
+	&dev_attr_bmcfw_version.attr,
+	NULL,
+};
+
+static struct attribute_group m10bmc_attr_group = {
+	.attrs = m10bmc_attrs,
+};
+
+static const struct attribute_group *m10bmc_dev_groups[] = {
+	&m10bmc_attr_group,
+	NULL
+};
+
+static int check_m10bmc_version(struct intel_m10bmc *m10bmc)
+{
+	unsigned int v;
+
+	if (m10bmc_raw_read(m10bmc, M10BMC_LEGACY_SYS_BASE + M10BMC_BUILD_VER,
+			    &v))
+		return -ENODEV;
+
+	if (v != 0xffffffff) {
+		dev_err(m10bmc->dev, "bad version M10BMC detected\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int m10bmc_spi_setup(struct spi_device *spi)
+{
+	/* try 32 bits bpw first then fall back to 8 bits bpw */
+	spi->mode = SPI_MODE_1;
+	spi->bits_per_word = 32;
+	if (!spi_setup(spi))
+		return 0;
+
+	spi->bits_per_word = 8;
+	return spi_setup(spi);
+}
+
+static int intel_m10_bmc_spi_probe(struct spi_device *spi)
+{
+	const struct spi_device_id *id = spi_get_device_id(spi);
+	struct device *dev = &spi->dev;
+	struct mfd_cell *cells;
+	struct intel_m10bmc *m10bmc;
+	int ret, n_cell;
+
+	ret = m10bmc_spi_setup(spi);
+	if (ret)
+		return ret;
+
+	m10bmc = devm_kzalloc(dev, sizeof(*m10bmc), GFP_KERNEL);
+	if (!m10bmc)
+		return -ENOMEM;
+
+	m10bmc->dev = dev;
+
+	m10bmc->regmap =
+		devm_regmap_init_spi_avmm(spi, &intel_m10bmc_regmap_config);
+	if (IS_ERR(m10bmc->regmap)) {
+		ret = PTR_ERR(m10bmc->regmap);
+		dev_err(dev, "Failed to allocate regmap: %d\n", ret);
+		return ret;
+	}
+
+	spi_set_drvdata(spi, m10bmc);
+
+	ret = check_m10bmc_version(m10bmc);
+	if (ret) {
+		dev_err(dev, "Failed to identify m10bmc hardware\n");
+		return ret;
+	}
+
+	switch (id->driver_data) {
+	case M10_N3000:
+		cells = m10bmc_pacn3000_subdevs;
+		n_cell = ARRAY_SIZE(m10bmc_pacn3000_subdevs);
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO, cells, n_cell,
+				   NULL, 0, NULL);
+	if (ret)
+		dev_err(dev, "Failed to register sub-devices: %d\n", ret);
+
+	return ret;
+}
+
+static const struct spi_device_id m10bmc_spi_id[] = {
+	{ "m10-n3000", M10_N3000 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, m10bmc_spi_id);
+
+static struct spi_driver intel_m10bmc_spi_driver = {
+	.driver = {
+		.name = "intel-m10-bmc",
+		.dev_groups = m10bmc_dev_groups,
+	},
+	.probe = intel_m10_bmc_spi_probe,
+	.id_table = m10bmc_spi_id,
+};
+
+module_spi_driver(intel_m10bmc_spi_driver);
+
+MODULE_DESCRIPTION("Intel Max10 BMC Device Driver");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("spi:intel-m10-bmc");
diff --git a/include/linux/mfd/intel-m10-bmc.h b/include/linux/mfd/intel-m10-bmc.h
new file mode 100644
index 0000000..4979756
--- /dev/null
+++ b/include/linux/mfd/intel-m10-bmc.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Driver Header File for Intel Max10 Board Management Controller chip.
+ *
+ * Copyright (C) 2018-2020 Intel Corporation, Inc.
+ *
+ */
+#ifndef __INTEL_M10_BMC_H
+#define __INTEL_M10_BMC_H
+
+#include <linux/regmap.h>
+
+#define M10BMC_LEGACY_SYS_BASE	0x300400
+#define M10BMC_SYS_BASE		0x300800
+#define M10BMC_MEM_END		0x200000fc
+
+/* Register offset of system registers */
+#define NIOS2_FW_VERSION	0x0
+#define M10BMC_TEST_REG		0x3c
+#define M10BMC_BUILD_VER	0x68
+#define M10BMC_VER_MAJOR_MSK	GENMASK(23, 16)
+#define M10BMC_VER_PCB_INFO_MSK	GENMASK(31, 24)
+
+/**
+ * struct intel_m10bmc - Intel Max10 BMC MFD device private data structure
+ * @dev: this device
+ * @regmap: the regmap used to access registers by m10bmc itself
+ */
+struct intel_m10bmc {
+	struct device *dev;
+	struct regmap *regmap;
+};
+
+/*
+ * register access helper functions.
+ *
+ * m10bmc_raw_read - read m10bmc register per addr
+ * m10bmc_sys_read - read m10bmc system register per offset
+ */
+static inline int
+m10bmc_raw_read(struct intel_m10bmc *m10bmc, unsigned int addr,
+		unsigned int *val)
+{
+	int ret;
+
+	ret = regmap_read(m10bmc->regmap, addr, val);
+	if (ret)
+		dev_err(m10bmc->dev, "fail to read raw reg %x: %d\n",
+			addr, ret);
+
+	return ret;
+}
+
+#define m10bmc_sys_read(m10bmc, offset, val) \
+	m10bmc_raw_read(m10bmc, M10BMC_SYS_BASE + (offset), val)
+
+#endif /* __INTEL_M10_BMC_H */
-- 
2.7.4