platform/x86/amd/pmc: Add dump_custom_stb module parameter

There have been instances when the default size (1M) of the STB is not
sufficient to get the complete traces of the failure. In such scenarios
we can use a module_param to enable full trace that shall contain more
debugging data. This is not a regular case and hence not enabling this
capability by default.

With this change, there will be two cases on how the driver fetches the
stb data:
1) A special case (proposed now) - which is required only for certain
platforms. Here, a new module param will be supplied to the driver that
will have a special PMFW supporting enhanced dram sizes for getting
the stb data. Without the special PMFW support, just setting the module
param will not help to get the enhanced stb data.

To adapt to this change, we will have a new amd_pmc_stb_handle_efr() to
handle enhanced firmware reporting mechanism. Note that, since num_samples
based r/w pointer offset calculation is not required for enhanced firmware
reporting we will have this mailbox command sent only in case of regular
STB cases.

2) Current code branch which fetches the stb data based on the parameters
like the num_samples, fsize and the r/w pointer.

Reviewed-by: Ilpo Järvinen <[email protected]>
Reviewed-by: Hans de Goede <[email protected]>
Co-developed-by: Harsh Jain <[email protected]>
Signed-off-by: Harsh Jain <[email protected]>
Signed-off-by: Sanket Goswami <[email protected]>
Signed-off-by: Shyam Sundar S K <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ij: Renamed flex_arr -> stb_data_arr]
Signed-off-by: Ilpo Järvinen <[email protected]>

Author: Shyam Sundar S K

drivers/platform/x86/amd/pmc/pmc.c

@@ -53,6 +53,7 @@
 
 /* STB Spill to DRAM Parameters */
 #define S2D_TELEMETRY_BYTES_MAX		0x100000U
+#define S2D_RSVD_RAM_SPACE		0x100000
 #define S2D_TELEMETRY_DRAMBYTES_MAX	0x1000000
 
 /* STB Spill to DRAM Message Definition */
@@ -165,6 +166,10 @@ static bool disable_workarounds;
 module_param(disable_workarounds, bool, 0644);
 MODULE_PARM_DESC(disable_workarounds, "Disable workarounds for platform bugs");
 
+static bool dump_custom_stb;
+module_param(dump_custom_stb, bool, 0644);
+MODULE_PARM_DESC(dump_custom_stb, "Enable to dump full STB buffer");
+
 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_read_stb(struct amd_pmc_dev *dev, u32 *buf);
@@ -241,6 +246,25 @@ static const struct file_operations amd_pmc_stb_debugfs_fops = {
 	.release = amd_pmc_stb_debugfs_release,
 };
 
+/* Enhanced STB Firmware Reporting Mechanism */
+static int amd_pmc_stb_handle_efr(struct file *filp)
+{
+	struct amd_pmc_dev *dev = filp->f_inode->i_private;
+	struct amd_pmc_stb_v2_data *stb_data_arr;
+	u32 fsize;
+
+	fsize = dev->dram_size - S2D_RSVD_RAM_SPACE;
+	stb_data_arr = kmalloc(struct_size(stb_data_arr, data, fsize), GFP_KERNEL);
+	if (!stb_data_arr)
+		return -ENOMEM;
+
+	stb_data_arr->size = fsize;
+	memcpy_fromio(stb_data_arr->data, dev->stb_virt_addr, fsize);
+	filp->private_data = stb_data_arr;
+
+	return 0;
+}
+
 static int amd_pmc_stb_debugfs_open_v2(struct inode *inode, struct file *filp)
 {
 	struct amd_pmc_dev *dev = filp->f_inode->i_private;
@@ -260,6 +284,14 @@ static int amd_pmc_stb_debugfs_open_v2(struct inode *inode, struct file *filp)
 	if (ret)
 		dev_dbg_once(dev->dev, "S2D force flush not supported: %d\n", ret);
 
+	/*
+	 * We have a custom stb size and the PMFW is supposed to give
+	 * the enhanced dram size. Note that we land here only for the
+	 * platforms that support enhanced dram size reporting.
+	 */
+	if (dump_custom_stb)
+		return amd_pmc_stb_handle_efr(filp);
+
 	/* Get the num_samples to calculate the last push location */
 	ret = amd_pmc_send_cmd(dev, S2D_NUM_SAMPLES, &num_samples, dev->s2d_msg_id, true);
 	/* Clear msg_port for other SMU operation */