[PATCH v1] x86: punit_atom: punit device state debug driver

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

The patch adds a debug driver, which dumps the power states
of all the North complex (NC) devices. This debug interface is
useful to figure out the NC IPs which blocks the S0ix
transitions on the platform. This is extremely useful during
enabling PM on customer platforms and derivatives.

This submission not a complete rewrite from the original
submission from Kumar P, Mahesh <mahesh.kumar.p.intel.com>.
https://lkml.org/lkml/2014/11/5/367
The changes are:
- Dropped changes to config for PMC_ATOM, as PMC_ATOM
is not just a debug driver as suggested by the change. It has
additional power off interface also.
- Instead of just using nc ("North complex") use punit_..
similar to south complex PMC. All the interfaces exposed
by this driver are provided by PUNIT.
- Removed pmc_config structure,  as we don't need to predefine
number of register, we want to dump. This way new register
can be added without changing NC_NUM_DEVICES.
- prefixed function with punit_
- The debugfs directory will be punit_atom, which is NC equivalent
of pmc_atom, which we already exposed by pmc_atom driver.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
 arch/x86/Kconfig.debug             |   9 ++
 arch/x86/kernel/Makefile           |   1 +
 arch/x86/kernel/punit_atom_debug.c | 170 +++++++++++++++++++++++++++++++++++++
 3 files changed, 180 insertions(+)
 create mode 100644 arch/x86/kernel/punit_atom_debug.c

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 20028da..9b85dfe 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -336,4 +336,13 @@ config X86_DEBUG_STATIC_CPU_HAS
 
 	  If unsure, say N.
 
+config PUNIT_ATOM_DEBUG
+	tristate "ATOM Punit debug driver"
+	depends on DEBUG_FS
+	select IOSF_MBI
+	---help---
+	  This is a debug driver, which gets the power states
+	  of all Punit North Complex devices.The power states of
+	  each IP is exposed as part of the debugfs interface.
+
 endmenu
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index cdb1b70..2ecbd55 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -110,6 +110,7 @@ obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o
 obj-$(CONFIG_TRACING)			+= tracepoint.o
 obj-$(CONFIG_IOSF_MBI)			+= iosf_mbi.o
 obj-$(CONFIG_PMC_ATOM)			+= pmc_atom.o
+obj-$(CONFIG_PUNIT_ATOM_DEBUG)		+= punit_atom_debug.o
 
 ###
 # 64 bit specific files
diff --git a/arch/x86/kernel/punit_atom_debug.c b/arch/x86/kernel/punit_atom_debug.c
new file mode 100644
index 0000000..6e7d4e5
--- /dev/null
+++ b/arch/x86/kernel/punit_atom_debug.c
@@ -0,0 +1,170 @@
+/*
+ * Intel SOC Punit device state debug driver
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/io.h>
+#include <asm/cpu_device_id.h>
+#include <asm/iosf_mbi.h>
+
+#define PUNIT_PORT		0x04
+#define PWRGT_STATUS		0x61 /* Power gate status reg */
+#define VED_SS_PM0		0x32 /* Subsystem config/status Video */
+#define ISP_SS_PM0		0x39 /* Subsystem config/status ISP */
+#define MIO_SS_PM		0x3B /* Subsystem config/status MIO */
+#define SSS_SHIFT		24
+#define RENDER_POS		0
+#define MEDIA_POS		2
+#define VLV_DISPLAY_POS		6
+#define CHT_DSP_SSS		0x36 /* Subsystem config/status DSP */
+#define CHT_DSP_SSS_POS		16
+
+struct punit_device {
+	char *name;
+	int reg;
+	int sss_pos;
+};
+
+static struct punit_device *punit_device;
+
+static const struct punit_device punit_device_byt[] = {
+	{ "GFX RENDER", PWRGT_STATUS, RENDER_POS },
+	{ "GFX MEDIA", PWRGT_STATUS, MEDIA_POS },
+	{ "DISPLAY", PWRGT_STATUS, VLV_DISPLAY_POS },
+	{ "VED", VED_SS_PM0, SSS_SHIFT},
+	{ "ISP", ISP_SS_PM0, SSS_SHIFT},
+	{ "MIO", MIO_SS_PM, SSS_SHIFT},
+	{ NULL}
+};
+
+static const struct punit_device punit_device_cht[] = {
+	{ "GFX RENDER", PWRGT_STATUS, RENDER_POS },
+	{ "GFX MEDIA", PWRGT_STATUS, MEDIA_POS },
+	{ "DSP", CHT_DSP_SSS,  CHT_DSP_SSS_POS },
+	{ "VED", VED_SS_PM0, SSS_SHIFT},
+	{ "ISP", ISP_SS_PM0, SSS_SHIFT},
+	{ "MIO", MIO_SS_PM, SSS_SHIFT},
+	{ NULL}
+};
+
+static const char * const dstates[] = {"D0", "D0i1", "D0i2", "D0i3"};
+
+static int punit_dev_state_show(struct seq_file *seq_file, void *unused)
+{
+	u32 punit_pwr_status;
+	int index;
+	int status;
+
+	seq_puts(seq_file, "\n\nPUNIT NORTH COMPLEX DEVICES :\n");
+	while (punit_device->name) {
+		status = iosf_mbi_read(PUNIT_PORT, BT_MBI_PMC_READ,
+				       punit_device->reg,
+				       &punit_pwr_status);
+		if (status)
+			seq_printf(seq_file, "%9s : Read Failed\n",
+				   punit_device->name);
+		else  {
+			index = (punit_pwr_status >> punit_device->sss_pos) & 3;
+			seq_printf(seq_file, "%9s : %s\n", punit_device->name,
+				   dstates[index]);
+		}
+		punit_device++;
+	}
+
+	return 0;
+}
+
+static int punit_dev_state_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, punit_dev_state_show, inode->i_private);
+}
+
+static const struct file_operations punit_dev_state_ops = {
+	.open		= punit_dev_state_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static struct dentry *punit_dbg_file;
+
+static int punit_dbgfs_register(void)
+{
+	static struct dentry *dev_state;
+
+	punit_dbg_file = debugfs_create_dir("punit_atom", NULL);
+	if (!punit_dbg_file)
+		return -ENXIO;
+
+	dev_state = debugfs_create_file("dev_state", S_IFREG | S_IRUGO,
+					 punit_dbg_file, NULL,
+					 &punit_dev_state_ops);
+	if (!dev_state) {
+		pr_err("punit_dev_state register failed\n");
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static void punit_dbgfs_unregister(void)
+{
+	debugfs_remove_recursive(punit_dbg_file);
+}
+
+#define ICPU(model, drv_data) \
+	{ X86_VENDOR_INTEL, 6, model, X86_FEATURE_MWAIT,\
+	  (kernel_ulong_t)&drv_data }
+
+static const struct x86_cpu_id intel_punit_cpu_ids[] = {
+	ICPU(0x4c, punit_device_cht),
+	ICPU(0x37, punit_device_byt),
+	{}
+};
+
+MODULE_DEVICE_TABLE(x86cpu, intel_punit_cpu_ids);
+
+static int __init punit_atom_debug_init(void)
+{
+	const struct x86_cpu_id *id;
+	int ret;
+
+	id = x86_match_cpu(intel_punit_cpu_ids);
+	if (!id)
+		return -ENODEV;
+
+	punit_device = (struct punit_device *)id->driver_data;
+
+	ret = punit_dbgfs_register();
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static void __exit punit_atom_debug_exit(void)
+{
+	punit_dbgfs_unregister();
+}
+
+module_init(punit_atom_debug_init);
+module_exit(punit_atom_debug_exit);
+
+MODULE_AUTHOR("Kumar P, Mahesh <mahesh.kumar.p.intel.com>");
+MODULE_DESCRIPTION("Driver for Punit devices states debugging");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1