diff mbox series

[v22,5/7] soc: mediatek: SVS: add debug commands

Message ID 20220127033956.24585-6-roger.lu@mediatek.com
State Superseded
Headers show
Series soc: mediatek: SVS: introduce MTK SVS engine | expand

Commit Message

Roger Lu Jan. 27, 2022, 3:39 a.m. UTC
The purpose of SVS is to help find the suitable voltages
for DVFS. Therefore, if SVS bank voltages are concerned
to be wrong, we can adjust SVS bank voltages by this patch.

Signed-off-by: Roger Lu <roger.lu@mediatek.com>
---
 drivers/soc/mediatek/mtk-svs.c | 321 ++++++++++++++++++++++++++++++++-
 1 file changed, 318 insertions(+), 3 deletions(-)

Comments

AngeloGioacchino Del Regno Jan. 31, 2022, 11:11 a.m. UTC | #1
Il 27/01/22 04:39, Roger Lu ha scritto:
> The purpose of SVS is to help find the suitable voltages
> for DVFS. Therefore, if SVS bank voltages are concerned
> to be wrong, we can adjust SVS bank voltages by this patch.
> 
> Signed-off-by: Roger Lu <roger.lu@mediatek.com>


Hello Roger,
I was thinking about what this patch is adding... and I have a few considerations.

It's nice to have a debugging mechanism to read the status and dump registers, as
that's very helpful when doing heavy debugging of the IP... but adding the
possibility to write a voltage offset may be very dangerous: think about the case
in which, either for misconfiguration, or for any other reason, the debugfs entry
that allows writing voffset becomes user-writable, or a user writes an impossibly
high voffset.
In case a very low (negative) voffset is entered, the platform would crash (denial
of service); if a very high voffset is entered, hardware damage may occur.

For this reason, there are two proposals:
1. If you want to keep the debugfs voffset write, please constrain the permissible
    voffset to an acceptable range that at least makes it unlikely to damage the HW;
    Moreover, since voffset write is a feature that would be used in very limited
    debugging cases, I think that this should be implemented over a build-time
    configuration barrier... something like CONFIG_MTK_SVS_DEBUG_ALLOW_WRITE, or
    similar;
2. Since it's very unlikely for someone to really play that much with a voltage
    offset during runtime, and since this looks like something very machine specific
    (perhaps addressing board-specific quirks?), I would suggest to add this as a
    device-tree parameter instead, such as "mediatek,svs-voffset", as it is indeed
    possible to specify both positive or negative values in DT.

I would prefer proposal 2, as it looks generally cleaner and way less risky.

Regards,
Angelo
Roger Lu Feb. 15, 2022, 9:08 a.m. UTC | #2
Hi AngeloGioacchino,

Excuse me for the late reply.

On Mon, 2022-01-31 at 12:11 +0100, AngeloGioacchino Del Regno wrote:
> Il 27/01/22 04:39, Roger Lu ha scritto:
> > The purpose of SVS is to help find the suitable voltages
> > for DVFS. Therefore, if SVS bank voltages are concerned
> > to be wrong, we can adjust SVS bank voltages by this patch.
> > 
> > Signed-off-by: Roger Lu <roger.lu@mediatek.com>
> 
> 
> Hello Roger,
> I was thinking about what this patch is adding... and I have a few
> considerations.
> 
> It's nice to have a debugging mechanism to read the status and dump registers,
> as
> that's very helpful when doing heavy debugging of the IP... but adding the
> possibility to write a voltage offset may be very dangerous: think about the
> case
> in which, either for misconfiguration, or for any other reason, the debugfs
> entry
> that allows writing voffset becomes user-writable, or a user writes an
> impossibly
> high voffset.
> In case a very low (negative) voffset is entered, the platform would crash
> (denial
> of service); if a very high voffset is entered, hardware damage may occur.
> 
> For this reason, there are two proposals:
> 1. If you want to keep the debugfs voffset write, please constrain the
> permissible
>     voffset to an acceptable range that at least makes it unlikely to damage
> the HW;
>     Moreover, since voffset write is a feature that would be used in very
> limited
>     debugging cases, I think that this should be implemented over a build-time
>     configuration barrier... something like CONFIG_MTK_SVS_DEBUG_ALLOW_WRITE,
> or
>     similar;
> 2. Since it's very unlikely for someone to really play that much with a
> voltage
>     offset during runtime, and since this looks like something very machine
> specific
>     (perhaps addressing board-specific quirks?), I would suggest to add this
> as a
>     device-tree parameter instead, such as "mediatek,svs-voffset", as it is
> indeed
>     possible to specify both positive or negative values in DT.
> 
> I would prefer proposal 2, as it looks generally cleaner and way less risky.

Thanks for raising the considerations and give these great suggestions for us to
think about. Since these voffset read/write commands are used seldomly, we
decide to remove them for better system security.

> 
> Regards,
> Angelo
AngeloGioacchino Del Regno Feb. 15, 2022, 9:10 a.m. UTC | #3
Il 15/02/22 10:08, Roger Lu ha scritto:
> Hi AngeloGioacchino,
> 
> Excuse me for the late reply.

Hi Roger,
no worries about that.

> 
> On Mon, 2022-01-31 at 12:11 +0100, AngeloGioacchino Del Regno wrote:
>> Il 27/01/22 04:39, Roger Lu ha scritto:
>>> The purpose of SVS is to help find the suitable voltages
>>> for DVFS. Therefore, if SVS bank voltages are concerned
>>> to be wrong, we can adjust SVS bank voltages by this patch.
>>>
>>> Signed-off-by: Roger Lu <roger.lu@mediatek.com>
>>
>>
>> Hello Roger,
>> I was thinking about what this patch is adding... and I have a few
>> considerations.
>>
>> It's nice to have a debugging mechanism to read the status and dump registers,
>> as
>> that's very helpful when doing heavy debugging of the IP... but adding the
>> possibility to write a voltage offset may be very dangerous: think about the
>> case
>> in which, either for misconfiguration, or for any other reason, the debugfs
>> entry
>> that allows writing voffset becomes user-writable, or a user writes an
>> impossibly
>> high voffset.
>> In case a very low (negative) voffset is entered, the platform would crash
>> (denial
>> of service); if a very high voffset is entered, hardware damage may occur.
>>
>> For this reason, there are two proposals:
>> 1. If you want to keep the debugfs voffset write, please constrain the
>> permissible
>>      voffset to an acceptable range that at least makes it unlikely to damage
>> the HW;
>>      Moreover, since voffset write is a feature that would be used in very
>> limited
>>      debugging cases, I think that this should be implemented over a build-time
>>      configuration barrier... something like CONFIG_MTK_SVS_DEBUG_ALLOW_WRITE,
>> or
>>      similar;
>> 2. Since it's very unlikely for someone to really play that much with a
>> voltage
>>      offset during runtime, and since this looks like something very machine
>> specific
>>      (perhaps addressing board-specific quirks?), I would suggest to add this
>> as a
>>      device-tree parameter instead, such as "mediatek,svs-voffset", as it is
>> indeed
>>      possible to specify both positive or negative values in DT.
>>
>> I would prefer proposal 2, as it looks generally cleaner and way less risky.
> 
> Thanks for raising the considerations and give these great suggestions for us to
> think about. Since these voffset read/write commands are used seldomly, we
> decide to remove them for better system security.
> 

Thank you for this ack, very much appreciated.
Eager to see v23!


>>
>> Regards,
>> Angelo
>
diff mbox series

Patch

diff --git a/drivers/soc/mediatek/mtk-svs.c b/drivers/soc/mediatek/mtk-svs.c
index be53470d439c..d3977de56335 100644
--- a/drivers/soc/mediatek/mtk-svs.c
+++ b/drivers/soc/mediatek/mtk-svs.c
@@ -6,6 +6,7 @@ 
 #include <linux/bits.h>
 #include <linux/clk.h>
 #include <linux/completion.h>
+#include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
@@ -23,6 +24,7 @@ 
 #include <linux/pm_qos.h>
 #include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
+#include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/thermal.h>
@@ -69,6 +71,39 @@ 
 
 static DEFINE_SPINLOCK(svs_lock);
 
+#define debug_fops_ro(name)						\
+	static int svs_##name##_debug_open(struct inode *inode,		\
+					   struct file *filp)		\
+	{								\
+		return single_open(filp, svs_##name##_debug_show,	\
+				   inode->i_private);			\
+	}								\
+	static const struct file_operations svs_##name##_debug_fops = {	\
+		.owner = THIS_MODULE,					\
+		.open = svs_##name##_debug_open,			\
+		.read = seq_read,					\
+		.llseek = seq_lseek,					\
+		.release = single_release,				\
+	}
+
+#define debug_fops_rw(name)						\
+	static int svs_##name##_debug_open(struct inode *inode,		\
+					   struct file *filp)		\
+	{								\
+		return single_open(filp, svs_##name##_debug_show,	\
+				   inode->i_private);			\
+	}								\
+	static const struct file_operations svs_##name##_debug_fops = {	\
+		.owner = THIS_MODULE,					\
+		.open = svs_##name##_debug_open,			\
+		.read = seq_read,					\
+		.write = svs_##name##_debug_write,			\
+		.llseek = seq_lseek,					\
+		.release = single_release,				\
+	}
+
+#define svs_dentry_data(name)	{__stringify(name), &svs_##name##_debug_fops}
+
 /**
  * enum svsb_phase - svs bank phase enumeration
  * @SVSB_PHASE_ERROR: svs bank encounters unexpected condition
@@ -269,6 +304,8 @@  struct svs_platform_data {
  * @tzone_name: thermal zone name
  * @phase: bank current phase
  * @volt_od: bank voltage overdrive
+ * @voffset: bank voltage offset for debug purpose
+ * @reg_data: bank register data in different phase for debug purpose
  * @pm_runtime_enabled_count: bank pm runtime enabled count
  * @mode_support: bank mode support.
  * @freq_base: reference frequency for bank init
@@ -328,6 +365,8 @@  struct svs_bank {
 	char *tzone_name;
 	enum svsb_phase phase;
 	s32 volt_od;
+	s32 voffset;
+	u32 reg_data[SVSB_PHASE_MAX][SVS_REG_MAX];
 	u32 pm_runtime_enabled_count;
 	u32 mode_support;
 	u32 freq_base;
@@ -434,14 +473,15 @@  static int svs_adjust_pm_opp_volts(struct svs_bank *svsb)
 			/* do nothing */
 			goto unlock_mutex;
 		case SVSB_PHASE_INIT02:
-			svsb_volt = max(svsb->volt[i], svsb->vmin);
+			svsb_volt = max(svsb->volt[i] + svsb->voffset,
+					svsb->vmin);
 			opp_volt = svs_bank_volt_to_opp_volt(svsb_volt,
 							     svsb->volt_step,
 							     svsb->volt_base);
 			break;
 		case SVSB_PHASE_MON:
-			svsb_volt = max(svsb->volt[i] + temp_voffset,
-					svsb->vmin);
+			svsb_volt = max(svsb->volt[i] + temp_voffset +
+					svsb->voffset, svsb->vmin);
 			opp_volt = svs_bank_volt_to_opp_volt(svsb_volt,
 							     svsb->volt_step,
 							     svsb->volt_base);
@@ -470,6 +510,257 @@  static int svs_adjust_pm_opp_volts(struct svs_bank *svsb)
 	return ret;
 }
 
+static int svs_dump_debug_show(struct seq_file *m, void *p)
+{
+	struct svs_platform *svsp = (struct svs_platform *)m->private;
+	struct svs_bank *svsb;
+	unsigned long svs_reg_addr;
+	u32 idx, i, j, bank_id;
+
+	for (i = 0; i < svsp->efuse_max; i++)
+		if (svsp->efuse && svsp->efuse[i])
+			seq_printf(m, "M_HW_RES%d = 0x%08x\n",
+				   i, svsp->efuse[i]);
+
+	for (i = 0; i < svsp->tefuse_max; i++)
+		if (svsp->tefuse)
+			seq_printf(m, "THERMAL_EFUSE%d = 0x%08x\n",
+				   i, svsp->tefuse[i]);
+
+	for (bank_id = 0, idx = 0; idx < svsp->bank_max; idx++, bank_id++) {
+		svsb = &svsp->banks[idx];
+
+		for (i = SVSB_PHASE_INIT01; i <= SVSB_PHASE_MON; i++) {
+			seq_printf(m, "Bank_number = %u\n", bank_id);
+
+			if (i == SVSB_PHASE_INIT01 || i == SVSB_PHASE_INIT02)
+				seq_printf(m, "mode = init%d\n", i);
+			else if (i == SVSB_PHASE_MON)
+				seq_puts(m, "mode = mon\n");
+			else
+				seq_puts(m, "mode = error\n");
+
+			for (j = DESCHAR; j < SVS_REG_MAX; j++) {
+				svs_reg_addr = (unsigned long)(svsp->base +
+							       svsp->regs[j]);
+				seq_printf(m, "0x%08lx = 0x%08x\n",
+					   svs_reg_addr, svsb->reg_data[i][j]);
+			}
+		}
+	}
+
+	return 0;
+}
+
+debug_fops_ro(dump);
+
+static int svs_enable_debug_show(struct seq_file *m, void *v)
+{
+	struct svs_bank *svsb = (struct svs_bank *)m->private;
+
+	switch (svsb->phase) {
+	case SVSB_PHASE_ERROR:
+		seq_puts(m, "disabled\n");
+		break;
+	case SVSB_PHASE_INIT01:
+		seq_puts(m, "init1\n");
+		break;
+	case SVSB_PHASE_INIT02:
+		seq_puts(m, "init2\n");
+		break;
+	case SVSB_PHASE_MON:
+		seq_puts(m, "mon mode\n");
+		break;
+	default:
+		seq_puts(m, "unknown\n");
+		break;
+	}
+
+	return 0;
+}
+
+static ssize_t svs_enable_debug_write(struct file *filp,
+				      const char __user *buffer,
+				      size_t count, loff_t *pos)
+{
+	struct svs_bank *svsb = file_inode(filp)->i_private;
+	struct svs_platform *svsp = dev_get_drvdata(svsb->dev);
+	unsigned long flags;
+	int enabled, ret;
+	char *buf = NULL;
+
+	if (count >= PAGE_SIZE)
+		return -EINVAL;
+
+	buf = (char *)memdup_user_nul(buffer, count);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	ret = kstrtoint(buf, 10, &enabled);
+	if (ret)
+		return ret;
+
+	if (!enabled) {
+		spin_lock_irqsave(&svs_lock, flags);
+		svsp->pbank = svsb;
+		svsb->mode_support = SVSB_MODE_ALL_DISABLE;
+		svs_switch_bank(svsp);
+		svs_writel_relaxed(svsp, SVSB_EN_OFF, SVSEN);
+		svs_writel_relaxed(svsp, SVSB_INTSTS_CLEAN, INTSTS);
+		spin_unlock_irqrestore(&svs_lock, flags);
+
+		svsb->phase = SVSB_PHASE_ERROR;
+		svs_adjust_pm_opp_volts(svsb);
+	}
+
+	kfree(buf);
+
+	return count;
+}
+
+debug_fops_rw(enable);
+
+static int svs_status_debug_show(struct seq_file *m, void *v)
+{
+	struct svs_bank *svsb = (struct svs_bank *)m->private;
+	struct dev_pm_opp *opp;
+	int tzone_temp = 0, ret;
+	u32 i;
+
+	ret = thermal_zone_get_temp(svsb->tzd, &tzone_temp);
+	if (ret)
+		seq_printf(m, "%s: temperature ignore\n", svsb->name);
+	else
+		seq_printf(m, "%s: temperature = %d\n", svsb->name, tzone_temp);
+
+	for (i = 0; i < svsb->opp_count; i++) {
+		opp = dev_pm_opp_find_freq_exact(svsb->opp_dev,
+						 svsb->opp_dfreq[i], true);
+		if (IS_ERR(opp)) {
+			seq_printf(m, "%s: cannot find freq = %u (%ld)\n",
+				   svsb->name, svsb->opp_dfreq[i],
+				   PTR_ERR(opp));
+			return PTR_ERR(opp);
+		}
+
+		seq_printf(m, "opp_freq[%02u]: %u, opp_volt[%02u]: %lu, ",
+			   i, svsb->opp_dfreq[i], i,
+			   dev_pm_opp_get_voltage(opp));
+		seq_printf(m, "svsb_volt[%02u]: 0x%x, freq_pct[%02u]: %u\n",
+			   i, svsb->volt[i], i, svsb->freq_pct[i]);
+		dev_pm_opp_put(opp);
+	}
+
+	return 0;
+}
+
+debug_fops_ro(status);
+
+static int svs_voffset_debug_show(struct seq_file *m, void *v)
+{
+	struct svs_bank *svsb = (struct svs_bank *)m->private;
+
+	seq_printf(m, "%d\n", svsb->voffset);
+
+	return 0;
+}
+
+static ssize_t svs_voffset_debug_write(struct file *filp,
+				       const char __user *buffer,
+				       size_t count, loff_t *pos)
+{
+	struct svs_bank *svsb = file_inode(filp)->i_private;
+	char *buf = NULL;
+	s32 voffset;
+
+	if (count >= PAGE_SIZE)
+		return -EINVAL;
+
+	buf = (char *)memdup_user_nul(buffer, count);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	if (!kstrtoint(buf, 10, &voffset)) {
+		svsb->voffset = voffset;
+		svs_adjust_pm_opp_volts(svsb);
+	}
+
+	kfree(buf);
+
+	return count;
+}
+
+debug_fops_rw(voffset);
+
+static int svs_create_debug_cmds(struct svs_platform *svsp)
+{
+	struct svs_bank *svsb;
+	struct dentry *svs_dir, *svsb_dir, *file_entry;
+	const char *d = "/sys/kernel/debug/svs";
+	u32 i, idx;
+
+	struct svs_dentry {
+		const char *name;
+		const struct file_operations *fops;
+	};
+
+	struct svs_dentry svs_entries[] = {
+		svs_dentry_data(dump),
+	};
+
+	struct svs_dentry svsb_entries[] = {
+		svs_dentry_data(enable),
+		svs_dentry_data(status),
+		svs_dentry_data(voffset),
+	};
+
+	svs_dir = debugfs_create_dir("svs", NULL);
+	if (IS_ERR(svs_dir)) {
+		dev_err(svsp->dev, "cannot create %s: %ld\n",
+			d, PTR_ERR(svs_dir));
+		return PTR_ERR(svs_dir);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(svs_entries); i++) {
+		file_entry = debugfs_create_file(svs_entries[i].name, 0664,
+						 svs_dir, svsp,
+						 svs_entries[i].fops);
+		if (IS_ERR(file_entry)) {
+			dev_err(svsp->dev, "cannot create %s/%s: %ld\n",
+				d, svs_entries[i].name, PTR_ERR(file_entry));
+			return PTR_ERR(file_entry);
+		}
+	}
+
+	for (idx = 0; idx < svsp->bank_max; idx++) {
+		svsb = &svsp->banks[idx];
+
+		if (svsb->mode_support == SVSB_MODE_ALL_DISABLE)
+			continue;
+
+		svsb_dir = debugfs_create_dir(svsb->name, svs_dir);
+		if (IS_ERR(svsb_dir)) {
+			dev_err(svsp->dev, "cannot create %s/%s: %ld\n",
+				d, svsb->name, PTR_ERR(svsb_dir));
+			return PTR_ERR(svsb_dir);
+		}
+
+		for (i = 0; i < ARRAY_SIZE(svsb_entries); i++) {
+			file_entry = debugfs_create_file(svsb_entries[i].name,
+							 0664, svsb_dir, svsb,
+							 svsb_entries[i].fops);
+			if (IS_ERR(file_entry)) {
+				dev_err(svsp->dev, "no %s/%s/%s?: %ld\n",
+					d, svsb->name, svsb_entries[i].name,
+					PTR_ERR(file_entry));
+				return PTR_ERR(file_entry);
+			}
+		}
+	}
+
+	return 0;
+}
+
 static u32 interpolate(u32 f0, u32 f1, u32 v0, u32 v1, u32 fx)
 {
 	u32 vx;
@@ -594,6 +885,16 @@  static void svs_set_bank_phase(struct svs_platform *svsp,
 	}
 }
 
+static inline void svs_save_bank_register_data(struct svs_platform *svsp,
+					       enum svsb_phase phase)
+{
+	struct svs_bank *svsb = svsp->pbank;
+	enum svs_reg_index rg_i;
+
+	for (rg_i = DESCHAR; rg_i < SVS_REG_MAX; rg_i++)
+		svsb->reg_data[phase][rg_i] = svs_readl_relaxed(svsp, rg_i);
+}
+
 static inline void svs_error_isr_handler(struct svs_platform *svsp)
 {
 	struct svs_bank *svsb = svsp->pbank;
@@ -608,6 +909,8 @@  static inline void svs_error_isr_handler(struct svs_platform *svsp)
 		svs_readl_relaxed(svsp, SMSTATE1));
 	dev_err(svsb->dev, "TEMP = 0x%08x\n", svs_readl_relaxed(svsp, TEMP));
 
+	svs_save_bank_register_data(svsp, SVSB_PHASE_ERROR);
+
 	svsb->phase = SVSB_PHASE_ERROR;
 	svs_writel_relaxed(svsp, SVSB_EN_OFF, SVSEN);
 	svs_writel_relaxed(svsp, SVSB_INTSTS_CLEAN, INTSTS);
@@ -622,6 +925,8 @@  static inline void svs_init01_isr_handler(struct svs_platform *svsp)
 		 svs_readl_relaxed(svsp, VDESIGN30),
 		 svs_readl_relaxed(svsp, DCVALUES));
 
+	svs_save_bank_register_data(svsp, SVSB_PHASE_INIT01);
+
 	svsb->phase = SVSB_PHASE_INIT01;
 	svsb->dc_voffset_in = ~(svs_readl_relaxed(svsp, DCVALUES) &
 				GENMASK(15, 0)) + 1;
@@ -647,6 +952,8 @@  static inline void svs_init02_isr_handler(struct svs_platform *svsp)
 		 svs_readl_relaxed(svsp, VOP30),
 		 svs_readl_relaxed(svsp, DCVALUES));
 
+	svs_save_bank_register_data(svsp, SVSB_PHASE_INIT02);
+
 	svsb->phase = SVSB_PHASE_INIT02;
 	svsb->get_volts(svsp);
 
@@ -658,6 +965,8 @@  static inline void svs_mon_mode_isr_handler(struct svs_platform *svsp)
 {
 	struct svs_bank *svsb = svsp->pbank;
 
+	svs_save_bank_register_data(svsp, SVSB_PHASE_MON);
+
 	svsb->phase = SVSB_PHASE_MON;
 	svsb->get_volts(svsp);
 
@@ -1634,6 +1943,12 @@  static int svs_probe(struct platform_device *pdev)
 		goto svs_probe_iounmap;
 	}
 
+	ret = svs_create_debug_cmds(svsp);
+	if (ret) {
+		dev_err(svsp->dev, "svs create debug cmds fail: %d\n", ret);
+		goto svs_probe_iounmap;
+	}
+
 	return 0;
 
 svs_probe_iounmap: