[PATCH linux v4 20/20] drivers/fsi: Add SCOM client driver

[christopher.lee.bostic at gmail.com]

From: Chris Bostic <cbostic at us.ibm.com>

Add a bare bones SCOM engine device driver that registers
with the FSI bus.

V4 - Add put_scom and get_scom ops

Signed-off-by: Chris Bostic <cbostic at us.ibm.com>
---
 drivers/fsi/Kconfig    |   6 ++
 drivers/fsi/Makefile   |   1 +
 drivers/fsi/fsi-scom.c | 158 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 165 insertions(+)
 create mode 100644 drivers/fsi/fsi-scom.c

diff --git a/drivers/fsi/Kconfig b/drivers/fsi/Kconfig
index 69e7ee8..719a217 100644
--- a/drivers/fsi/Kconfig
+++ b/drivers/fsi/Kconfig
@@ -24,6 +24,12 @@ config FSI_MASTER_GPIO
 	select GPIO_DEVRES
 	---help---
 	This option enables a FSI master driver, using GPIO lines directly.
+
+config FSI_SCOM
+	tristate "SCOM FSI client"
+	depends on FSI
+	---help---
+	This option enables the SCOM FSI client device driver.
 endif
 
 endmenu
diff --git a/drivers/fsi/Makefile b/drivers/fsi/Makefile
index 2021ce5..3e31d9a 100644
--- a/drivers/fsi/Makefile
+++ b/drivers/fsi/Makefile
@@ -2,3 +2,4 @@
 obj-$(CONFIG_FSI) += fsi-core.o
 obj-$(CONFIG_FSI_MASTER_FAKE) += fsi-master-fake.o
 obj-$(CONFIG_FSI_MASTER_GPIO) += fsi-master-gpio.o
+obj-$(CONFIG_FSI_SCOM) += fsi-scom.o
diff --git a/drivers/fsi/fsi-scom.c b/drivers/fsi/fsi-scom.c
new file mode 100644
index 0000000..244e450
--- /dev/null
+++ b/drivers/fsi/fsi-scom.c
@@ -0,0 +1,158 @@
+/*
+ * SCOM FSI Client device driver
+ *
+ * Copyright (C) IBM Corporation 2016
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERGCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/fsi.h>
+#include <linux/module.h>
+#include <linux/cdev.h>
+#include <linux/delay.h>
+
+#define FSI_ENGID_SCOM		0x5
+
+#define SCOM_FSI2PIB_DELAY	50
+
+/* SCOM engine register set */
+#define SCOM_DATA0_REG		0x00
+#define SCOM_DATA1_REG		0x04
+#define SCOM_CMD_REG		0x08
+#define SCOM_RESET_REG		0x1C
+
+#define SCOM_RESET_CMD		0x80000000
+#define SCOM_WRITE_CMD		0x80000000
+
+static int scom_probe(struct device *);
+
+struct scom_device {
+	struct fsi_device *fsi_dev;
+	struct cdev *cdev;
+};
+
+struct scom_device scom_dev;
+
+struct fsi_device_id scom_ids[] = {
+	{
+		.engine_type = FSI_ENGID_SCOM,
+		.version = FSI_VERSION_ANY,
+	},
+	{ 0 }
+};
+
+struct fsi_driver scom_drv = {
+	.id_table = scom_ids,
+	.drv = {
+		.name = "scom",
+		.bus = &fsi_bus_type,
+		.probe = scom_probe,
+	}
+};
+
+static int put_scom(uint64_t value, uint32_t addr)
+{
+	int rc;
+	uint32_t data = SCOM_RESET_CMD;
+	struct scom_device *scom = &scom_dev;
+
+	rc = fsi_device_write(scom->fsi_dev, SCOM_RESET_REG, &data,
+				sizeof(uint32_t));
+	if (rc)
+		return rc;
+
+	data = (value >> 32) & 0xffffffff;
+	rc = fsi_device_write(scom->fsi_dev, SCOM_DATA0_REG, &data,
+				sizeof(uint32_t));
+	if (rc)
+		return rc;
+
+	data = value & 0xffffffff;
+	rc = fsi_device_write(scom->fsi_dev, SCOM_DATA1_REG, &data,
+				sizeof(uint32_t));
+	if (rc)
+		return rc;
+
+	data = SCOM_WRITE_CMD | addr;
+	return fsi_device_write(scom->fsi_dev, SCOM_CMD_REG, &data,
+				sizeof(uint32_t));
+}
+
+
+static int get_scom(uint64_t *value, uint32_t addr)
+{
+	uint32_t result, data;
+	struct scom_device *scom = &scom_dev;
+	int rc;
+
+	udelay(SCOM_FSI2PIB_DELAY);
+
+	data = addr;
+	rc = fsi_device_write(scom->fsi_dev, SCOM_CMD_REG, &data,
+				sizeof(uint32_t));
+	if (rc)
+		return rc;
+
+	rc = fsi_device_read(scom->fsi_dev, SCOM_DATA0_REG, &result,
+				sizeof(uint32_t));
+	if (rc)
+		return rc;
+
+	*value |= (uint64_t) result << 32;
+	rc = fsi_device_read(scom->fsi_dev, SCOM_DATA1_REG, &result,
+				sizeof(uint32_t));
+	if (rc)
+		return rc;
+
+	*value |= result;
+
+	return 0;
+}
+
+static int scom_probe(struct device *dev)
+{
+	struct fsi_device *fsi_dev = to_fsi_dev(dev);
+	struct scom_device *scom = &scom_dev;
+	int rc;
+	uint64_t data;
+
+	scom->fsi_dev = fsi_dev;
+	scom->cdev = cdev_alloc();
+	if (!scom->cdev)
+		return -ENOMEM;
+
+	scom->cdev->owner = THIS_MODULE;
+
+	/* todo: fill in and register cdev */
+	/* open, read, write, close file ops */
+
+	/* todo: user space linkage to get_scom / put_scom */
+	/*  engine init */
+
+	/* todo: how to enter test values? */
+	rc = get_scom(&data, 0);
+	data = 0;
+	rc = put_scom(data, 0);
+
+	return 0;
+}
+
+static int scom_init(void)
+{
+	return fsidrv_register(&scom_drv);
+}
+
+static void scom_exit(void)
+{
+	fsidrv_unregister(&scom_drv);
+}
+
+module_init(scom_init);
+module_exit(scom_exit);
-- 
1.8.2.2