[PATCH v9 8/9] mfd: Add Ampere's Altra SMpro MFD driver

[Quan Nguyen <quan@os.amperecomputing.com>]

Adds Multi-function devices driver for SMpro co-processor found on the
Mt.Jade hardware reference platform with Ampere's Altra processor family.

Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
---

Changes in v9:
  + Rename smpro-mfd.c to smpro-core.c                   [Lee Jones]
  + Fix include files in alphabetical order              [Lee Jones]
  + Add defines to avoid using magic numbers             [Lee Jones]
  + Return -EINVAL if device does not match              [Lee Jones]
  + Remove unneccessary comment                          [Lee Jones]
  + Refactor error path handling in smpro_core_read/write()   [Quan]

Changes in v8:
  + None

Changes in v7:
  + Smpro-mfd now significant changes in compare with simple-mfd-i2c
    driver, remove the copyright note about simple-mfd-i2c    [Quan]
  + Install bus->read/write()  to handle multiple types of bus
    access.                                                   [Quan]
  + Update license to MODULE_LICENSE("GPL")                   [Quan]
  + Add others minor refactor the code                        [Quan]

Changes in v6:
  + Update license part to reflect that this driver is clone from
  simple-mfd-i2c driver [Quan]

Changes in v5:
  + Dropped the use of simple-mfd-i2c driver [Quan]
  + Introduced drivers/mfd/smpro-mfd.c driver to instantiate
  sub-devices. This is to avoid DT nodes without resource issue [Quan]
  + Revised commit message [Quan]

Changes in v4:
  + Add "depends on I2C" to fix build issue found by kernel test
  robot [Guenter]

Changes in v3:
  + None

Changes in v2:
  + Used 'struct of_device_id's .data attribute [Lee Jones]

 drivers/mfd/Kconfig      |  12 ++++
 drivers/mfd/Makefile     |   1 +
 drivers/mfd/smpro-core.c | 138 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 151 insertions(+)
 create mode 100644 drivers/mfd/smpro-core.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 8b93856de432..9e77f4762999 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -77,6 +77,18 @@ config MFD_AS3711
 	help
 	  Support for the AS3711 PMIC from AMS
 
+config MFD_SMPRO
+	tristate "Ampere Computing SMpro core driver"
+	depends on I2C
+	select MFD_CORE
+	select REGMAP_I2C
+	help
+	  Say yes here to enable SMpro driver support for Ampere's Altra
+	  processor family.
+
+	  Ampere's Altra SMpro exposes an I2C regmap interface that can
+	  be accessed by child devices.
+
 config MFD_AS3722
 	tristate "ams AS3722 Power Management IC"
 	select MFD_CORE
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 7ed3ef4a698c..9387c3ddab4e 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -271,6 +271,7 @@ obj-$(CONFIG_MFD_QCOM_PM8008)	+= qcom-pm8008.o
 
 obj-$(CONFIG_SGI_MFD_IOC3)	+= ioc3.o
 obj-$(CONFIG_MFD_SIMPLE_MFD_I2C)	+= simple-mfd-i2c.o
+obj-$(CONFIG_MFD_SMPRO)		+= smpro-core.o
 obj-$(CONFIG_MFD_INTEL_M10_BMC)   += intel-m10-bmc.o
 
 obj-$(CONFIG_MFD_ATC260X)	+= atc260x-core.o
diff --git a/drivers/mfd/smpro-core.c b/drivers/mfd/smpro-core.c
new file mode 100644
index 000000000000..d7729cf70378
--- /dev/null
+++ b/drivers/mfd/smpro-core.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Ampere Altra Family SMPro core driver
+ * Copyright (c) 2022, Ampere Computing LLC
+ */
+
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/regmap.h>
+
+/* Identification Registers */
+#define MANUFACTURER_ID_REG     0x02
+#define AMPERE_MANUFACTURER_ID  0xCD3A
+
+#define CORE_CE_ERR_DATA        0x82
+#define CORE_UE_ERR_DATA        0x85
+#define MEM_CE_ERR_DATA         0x92
+#define MEM_UE_ERR_DATA         0x95
+#define PCIE_CE_ERR_DATA        0xC2
+#define PCIE_UE_ERR_DATA        0xC5
+#define OTHER_CE_ERR_DATA       0xD2
+#define OTHER_UE_ERR_DATA       0xDA
+
+static int smpro_core_write(void *context, const void *data, size_t count)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+	int ret;
+
+	ret = i2c_master_send(i2c, data, count);
+	if (unlikely(ret != count))
+		return (ret < 0) ? ret : -EIO;
+
+	return 0;
+}
+
+static int smpro_core_read(void *context, const void *reg, size_t reg_size,
+			   void *val, size_t val_size)
+{
+	struct device *dev = context;
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct i2c_msg xfer[2];
+	unsigned char buf[2];
+	int ret;
+
+	xfer[0].addr = i2c->addr;
+	xfer[0].flags = 0;
+
+	buf[0] = *(u8 *)reg;
+	buf[1] = val_size;
+	xfer[0].len = 2;
+	xfer[0].buf = buf;
+
+	xfer[1].addr = i2c->addr;
+	xfer[1].flags = I2C_M_RD;
+	xfer[1].len = val_size;
+	xfer[1].buf = val;
+
+	ret = i2c_transfer(i2c->adapter, xfer, 2);
+	if (unlikely(ret != 2))
+		return (ret < 0) ? ret : -EIO;
+
+	return 0;
+}
+
+static const struct regmap_bus smpro_regmap_bus = {
+	.read = smpro_core_read,
+	.write = smpro_core_write,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
+static bool smpro_core_readable_noinc_reg(struct device *dev, unsigned int reg)
+{
+	return  (reg == CORE_CE_ERR_DATA || reg == CORE_UE_ERR_DATA ||
+		 reg == MEM_CE_ERR_DATA || reg == MEM_UE_ERR_DATA ||
+		 reg == PCIE_CE_ERR_DATA || reg == PCIE_UE_ERR_DATA ||
+		 reg == OTHER_CE_ERR_DATA || reg == OTHER_UE_ERR_DATA);
+}
+
+static const struct regmap_config smpro_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.readable_noinc_reg = smpro_core_readable_noinc_reg,
+};
+
+static const struct mfd_cell smpro_devs[] = {
+	MFD_CELL_NAME("smpro-hwmon"),
+	MFD_CELL_NAME("smpro-errmon"),
+	MFD_CELL_NAME("smpro-misc"),
+};
+
+static int smpro_core_probe(struct i2c_client *i2c)
+{
+	const struct regmap_config *config;
+	struct regmap *regmap;
+	unsigned int val;
+	int ret;
+
+	config = device_get_match_data(&i2c->dev);
+	if (!config)
+		return -EINVAL;
+
+	regmap = devm_regmap_init(&i2c->dev, &smpro_regmap_bus, &i2c->dev, config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	ret = regmap_read(regmap, MANUFACTURER_ID_REG, &val);
+	if (ret)
+		return ret;
+
+	if (val != AMPERE_MANUFACTURER_ID)
+		return -ENODEV;
+
+	return devm_mfd_add_devices(&i2c->dev, PLATFORM_DEVID_AUTO,
+				    smpro_devs, ARRAY_SIZE(smpro_devs), NULL, 0, NULL);
+}
+
+static const struct of_device_id smpro_core_of_match[] = {
+	{ .compatible = "ampere,smpro", .data = &smpro_regmap_config },
+	{}
+};
+MODULE_DEVICE_TABLE(of, smpro_core_of_match);
+
+static struct i2c_driver smpro_core_driver = {
+	.probe_new = smpro_core_probe,
+	.driver = {
+		.name = "smpro-core",
+		.of_match_table = smpro_core_of_match,
+	},
+};
+module_i2c_driver(smpro_core_driver);
+
+MODULE_AUTHOR("Quan Nguyen <quan@os.amperecomputing.com>");
+MODULE_DESCRIPTION("SMPRO CORE - I2C driver");
+MODULE_LICENSE("GPL");
-- 
2.35.1