On 10/29/2021 12:23, Sanket Goswami wrote:
STB (Smart Trace Buffer), is a debug trace buffer which is used to help
isolate failures by analyzing the last feature that a system was running
before hitting a failure. This nonintrusive way is always running in the
background and trace is stored into the SoC.
This patch provides mechanism to access the STB buffer using the read
and write routines.
Co-developed-by: Shyam Sundar S K <Shyam-sundar.S-k@xxxxxxx>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@xxxxxxx>
Signed-off-by: Sanket Goswami <Sanket.Goswami@xxxxxxx>
Tested-by: Scott Bruce <smbruce@xxxxxxxxx>
---
Changes in v5:
- Use kfree() only once in .open as suggested by Hans.
Changes in v4:
- Use kzalloc() for memory allocation.
Changes in v3:
- Use sizeof(u32) with multiplier as suggested by Mark Gross.
Changes in v2:
- Create amd_pmc_stb_debugfs_fops structure to get STB data.
- Address review comments from Hans.
drivers/platform/x86/amd-pmc.c | 127 +++++++++++++++++++++++++++++++++
1 file changed, 127 insertions(+)
diff --git a/drivers/platform/x86/amd-pmc.c b/drivers/platform/x86/amd-pmc.c
index ea099f7759f2..a39354ea96c4 100644
--- a/drivers/platform/x86/amd-pmc.c
+++ b/drivers/platform/x86/amd-pmc.c
@@ -35,6 +35,12 @@
#define AMD_PMC_SCRATCH_REG_CZN 0x94
#define AMD_PMC_SCRATCH_REG_YC 0xD14
+/* STB Registers */
+#define AMD_PMC_STB_INDEX_ADDRESS 0xF8
+#define AMD_PMC_STB_INDEX_DATA 0xFC
+#define AMD_PMC_STB_PMI_0 0x03E30600
+#define AMD_PMC_STB_PREDEF 0xC6000001
+
/* Base address of SMU for mapping physical address to virtual address */
#define AMD_PMC_SMU_INDEX_ADDRESS 0xB8
#define AMD_PMC_SMU_INDEX_DATA 0xBC
@@ -82,6 +88,7 @@
#define SOC_SUBSYSTEM_IP_MAX 12
#define DELAY_MIN_US 2000
#define DELAY_MAX_US 3000
+#define FIFO_SIZE 4096
enum amd_pmc_def {
MSG_TEST = 0x01,
MSG_OS_HINT_PCO,
@@ -128,8 +135,14 @@ struct amd_pmc_dev {
#endif /* CONFIG_DEBUG_FS */
};
+static bool enable_stb;
+module_param(enable_stb, bool, 0644);
+MODULE_PARM_DESC(enable_stb, "Enable the STB debug mechanism");
+
static struct amd_pmc_dev pmc;
static int amd_pmc_send_cmd(struct amd_pmc_dev *dev, u32 arg, u32 *data, u8 msg, bool ret);
+static int amd_pmc_write_stb(struct amd_pmc_dev *dev, u32 data);
+static int amd_pmc_read_stb(struct amd_pmc_dev *dev, u32 *buf);
static inline u32 amd_pmc_reg_read(struct amd_pmc_dev *dev, int reg_offset)
{
@@ -176,6 +189,50 @@ static int amd_pmc_get_smu_version(struct amd_pmc_dev *dev)
return 0;
}
+static int amd_pmc_stb_debugfs_open(struct inode *inode, struct file *filp)
+{
+ struct amd_pmc_dev *dev = filp->f_inode->i_private;
+ u32 size = FIFO_SIZE * sizeof(u32);
+ u32 *buf;
+ int rc;
+
+ buf = kzalloc(size, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ rc = amd_pmc_read_stb(dev, buf);
+ if (rc) {
+ kfree(buf);
+ return rc;
+ }
+
+ filp->private_data = buf;
+ return rc;
+}
+
+static ssize_t amd_pmc_stb_debugfs_read(struct file *filp, char __user *buf, size_t size,
+ loff_t *pos)
+{
+ if (!filp->private_data)
+ return -EINVAL;
+
+ return simple_read_from_buffer(buf, size, pos, filp->private_data,
+ FIFO_SIZE * sizeof(u32));
+}
+
+static int amd_pmc_stb_debugfs_release(struct inode *inode, struct file *filp)
+{
+ kfree(filp->private_data);
+ return 0;
+}
+
+const struct file_operations amd_pmc_stb_debugfs_fops = {
+ .owner = THIS_MODULE,
+ .open = amd_pmc_stb_debugfs_open,
+ .read = amd_pmc_stb_debugfs_read,
+ .release = amd_pmc_stb_debugfs_release,
+};
+
static int amd_pmc_idlemask_read(struct amd_pmc_dev *pdev, struct device *dev,
struct seq_file *s)
{
@@ -289,6 +346,10 @@ static void amd_pmc_dbgfs_register(struct amd_pmc_dev *dev)
&s0ix_stats_fops);
debugfs_create_file("amd_pmc_idlemask", 0644, dev->dbgfs_dir, dev,
&amd_pmc_idlemask_fops);
+ /* Enable STB only when the module_param is set */
+ if (enable_stb)
+ debugfs_create_file("stb_read", 0644, dev->dbgfs_dir, dev,
+ &amd_pmc_stb_debugfs_fops);
Have you considered using debugfs_create_blob instead? Wouldn't this
make it match the data type more closely?
}
#else
static inline void amd_pmc_dbgfs_register(struct amd_pmc_dev *dev)
@@ -485,6 +546,9 @@ static int __maybe_unused amd_pmc_suspend(struct device *dev)
if (rc)
dev_err(pdev->dev, "suspend failed\n");
+ if (enable_stb)
+ amd_pmc_write_stb(pdev, AMD_PMC_STB_PREDEF);
+
return rc;
}
@@ -505,6 +569,10 @@ static int __maybe_unused amd_pmc_resume(struct device *dev)
/* Dump the IdleMask to see the blockers */
amd_pmc_idlemask_read(pdev, dev, NULL);
+ /* Write data incremented by 1 to distinguish in stb_read */
+ if (enable_stb)
+ amd_pmc_write_stb(pdev, AMD_PMC_STB_PREDEF + 1);
+
return 0;
}
@@ -521,6 +589,65 @@ static const struct pci_device_id pmc_pci_ids[] = {
{ }
};
+static int amd_pmc_write_stb(struct amd_pmc_dev *dev, u32 data)
+{
+ int err;
+
+ err = pci_write_config_dword(dev->rdev, AMD_PMC_STB_INDEX_ADDRESS, AMD_PMC_STB_PMI_0);
+ if (err) {
+ dev_err(dev->dev, "failed to write addr in stb: 0x%X\n",
+ AMD_PMC_STB_INDEX_ADDRESS);
+ err = pcibios_err_to_errno(err);
+ goto err_pci_dev_put;
+ }
+
+ err = pci_write_config_dword(dev->rdev, AMD_PMC_STB_INDEX_DATA, data);
+ if (err) {
+ dev_err(dev->dev, "failed to write data in stb: 0x%X\n",
+ AMD_PMC_STB_INDEX_DATA);
+ err = pcibios_err_to_errno(err);
+ goto err_pci_dev_put;
+ }
+
+ return 0;
+
+err_pci_dev_put:
+ pci_dev_put(dev->rdev);
+ return err;
+}
+
+static int amd_pmc_read_stb(struct amd_pmc_dev *dev, u32 *buf)
+{
+ int i, err;
+ u32 value;
+
+ err = pci_write_config_dword(dev->rdev, AMD_PMC_STB_INDEX_ADDRESS, AMD_PMC_STB_PMI_0);
+ if (err) {
+ dev_err(dev->dev, "error writing addr to stb: 0x%X\n",
+ AMD_PMC_STB_INDEX_ADDRESS);
+ err = pcibios_err_to_errno(err);
+ goto err_pci_dev_put;
+ }
+
+ for (i = 0; i < FIFO_SIZE; i++) {
+ err = pci_read_config_dword(dev->rdev, AMD_PMC_STB_INDEX_DATA, &value);
+ if (err) {
+ dev_err(dev->dev, "error reading data from stb: 0x%X\n",
+ AMD_PMC_STB_INDEX_DATA);
+ err = pcibios_err_to_errno(err);
+ goto err_pci_dev_put;
+ }
+
+ *buf++ = value;
+ }
+
+ return 0;
+
+err_pci_dev_put:
+ pci_dev_put(dev->rdev);
+ return err;
+}
+
static int amd_pmc_probe(struct platform_device *pdev)
{
struct amd_pmc_dev *dev = &pmc;
