[PATCH v7 4/5] Add debugfs based error injection support in DWC

Shradha Todi
2025-02-22T10:59:11Z

Add support to provide error injection interface to userspace. This set
of debug registers are part of the RASDES feature present in DesignWare
PCIe controllers.

Signed-off-by: Shradha Todi <shradha.t@samsung.com>
---
Documentation/ABI/testing/debugfs-dwc-pcie | 70 ++++++++
.../controller/dwc/pcie-designware-debugfs.c | 165 +++++++++++++++++-
2 files changed, 233 insertions(+), 2 deletions(-)

diff --git a/Documentation/ABI/testing/debugfs-dwc-pcie b/Documentation/ABI/testing/debugfs-dwc-pcie
index e8ed34e988ef..6ee0897fe753 100644
--- a/Documentation/ABI/testing/debugfs-dwc-pcie
+++ b/Documentation/ABI/testing/debugfs-dwc-pcie
@@ -11,3 +11,73 @@ Contact: Shradha Todi <shradha.t@samsung.com>
Description: (RW) Write the lane number to be checked as valid or invalid. Read
will return the status of PIPE RXVALID signal of the selected lane.
The default selected lane is Lane0.
+
+What: /sys/kernel/debug/dwc_pcie_<dev>/rasdes_err_inj/<error>
+Date: Feburary 2025
+Contact: Shradha Todi <shradha.t@samsung.com>
+Description: rasdes_err_inj is the directory which can be used to inject errors in the
+ system. The possible errors that can be injected are:
+
+ 1) TLP LCRC error injection TX Path - tx_lcrc
+ 2) 16b CRC error injection of ACK/NAK DLLP - b16_crc_dllp
+ 3) 16b CRC error injection of Update-FC DLLP - b16_crc_upd_fc
+ 4) TLP ECRC error injection TX Path - tx_ecrc
+ 5) TLP's FCRC error injection TX Path - fcrc_tlp
+ 6) Parity error of TSOS - parity_tsos
+ 7) Parity error on SKPOS - parity_skpos
+ 8) LCRC error injection RX Path - rx_lcrc
+ 9) ECRC error injection RX Path - rx_ecrc
+ 10) TLPs SEQ# error - tlp_err_seq
+ 11) DLLPS ACK/NAK SEQ# error - ack_nak_dllp_seq
+ 12) ACK/NAK DLLPs transmission block - ack_nak_dllp
+ 13) UpdateFC DLLPs transmission block - upd_fc_dllp
+ 14) Always transmission for NAK DLLP - nak_dllp
+ 15) Invert SYNC header - inv_sync_hdr_sym
+ 16) COM/PAD TS1 order set - com_pad_ts1
+ 17) COM/PAD TS2 order set - com_pad_ts2
+ 18) COM/FTS FTS order set - com_fts
+ 19) COM/IDL E-idle order set - com_idl
+ 20) END/EDB symbol - end_edb
+ 21) STP/SDP symbol - stp_sdp
+ 22) COM/SKP SKP order set - com_skp
+ 23) Posted TLP Header credit value control - posted_tlp_hdr
+ 24) Non-Posted TLP Header credit value control - non_post_tlp_hdr
+ 25) Completion TLP Header credit value control - cmpl_tlp_hdr
+ 26) Posted TLP Data credit value control - posted_tlp_data
+ 27) Non-Posted TLP Data credit value control - non_post_tlp_data
+ 28) Completion TLP Data credit value control - cmpl_tlp_data
+ 29) Generates duplicate TLPs - duplicate_dllp
+ 30) Generates Nullified TLPs - nullified_tlp
+
+ (WO) Write to the attribute will prepare controller to inject the respective
+ error in the next transmission of data. Parameter required to write will
+ change in the following ways:
+
+ i) Errors 9) - 10) are sequence errors. The write command for these will be
+
+ echo <count> <diff> > /sys/kernel/debug/dwc_pcie_<dev>/rasdes_err_inj/<error>
+
+ <count>
+ Number of errors to be injected
+ <diff>
+ The difference to add or subtract from natural sequence number to
+ generate sequence error. Range (-4095 : 4095)
+
+ ii) Errors 23) - 28) are credit value error insertions. Write command:
+
+ echo <count> <diff> <vc> > /sys/kernel/debug/dwc_pcie_<dev>/rasdes_err_inj/<error>
+
+ <count>
+ Number of errors to be injected
+ <diff>
+ The difference to add or subtract from UpdateFC credit value.
+ Range (-4095 : 4095)
+ <vc>
+ Target VC number
+
+ iii) All other errors. Write command:
+
+ echo <count> > /sys/kernel/debug/dwc_pcie_<dev>/rasdes_err_inj/<error>
+
+ <count>
+ Number of errors to be injected
diff --git a/drivers/pci/controller/dwc/pcie-designware-debugfs.c b/drivers/pci/controller/dwc/pcie-designware-debugfs.c
index 3887a6996706..b7260edd2336 100644
--- a/drivers/pci/controller/dwc/pcie-designware-debugfs.c
+++ b/drivers/pci/controller/dwc/pcie-designware-debugfs.c
@@ -17,6 +17,20 @@
#define PIPE_DETECT_LANE BIT(17)
#define LANE_SELECT GENMASK(3, 0)

+#define ERR_INJ0_OFF 0x34
+#define EINJ_VAL_DIFF GENMASK(28, 16)
+#define EINJ_VC_NUM GENMASK(14, 12)
+#define EINJ_TYPE_SHIFT 8
+#define EINJ0_TYPE GENMASK(11, 8)
+#define EINJ1_TYPE BIT(8)
+#define EINJ2_TYPE GENMASK(9, 8)
+#define EINJ3_TYPE GENMASK(10, 8)
+#define EINJ4_TYPE GENMASK(10, 8)
+#define EINJ5_TYPE BIT(8)
+#define EINJ_COUNT GENMASK(7, 0)
+
+#define ERR_INJ_ENABLE_REG 0x30
+
#define DWC_DEBUGFS_BUF_MAX 128

/**
@@ -33,6 +47,72 @@ struct dwc_pcie_rasdes_info {
struct mutex reg_event_lock;
};

+/**
+ * struct dwc_pcie_rasdes_priv - Stores file specific private data information
+ * @pci: Reference to the dw_pcie structure
+ * @idx: Index to point to specific file related information in array of structs
+ *
+ * All debugfs files will have this struct as its private data.
+ */
+struct dwc_pcie_rasdes_priv {
+ struct dw_pcie *pci;
+ int idx;
+};
+
+/**
+ * struct dwc_pcie_err_inj - Store details about each error injection supported by DWC RASDES
+ * @name: Name of the error that can be injected
+ * @err_inj_group: Group number to which the error belongs to. Value can range from 0 - 5
+ * @err_inj_type: Each group can have multiple types of error
+ */
+struct dwc_pcie_err_inj {
+ const char *name;
+ u32 err_inj_group;
+ u32 err_inj_type;
+};
+
+static const struct dwc_pcie_err_inj err_inj_list[] = {
+ {"tx_lcrc", 0x0, 0x0},
+ {"b16_crc_dllp", 0x0, 0x1},
+ {"b16_crc_upd_fc", 0x0, 0x2},
+ {"tx_ecrc", 0x0, 0x3},
+ {"fcrc_tlp", 0x0, 0x4},
+ {"parity_tsos", 0x0, 0x5},
+ {"parity_skpos", 0x0, 0x6},
+ {"rx_lcrc", 0x0, 0x8},
+ {"rx_ecrc", 0x0, 0xb},
+ {"tlp_err_seq", 0x1, 0x0},
+ {"ack_nak_dllp_seq", 0x1, 0x1},
+ {"ack_nak_dllp", 0x2, 0x0},
+ {"upd_fc_dllp", 0x2, 0x1},
+ {"nak_dllp", 0x2, 0x2},
+ {"inv_sync_hdr_sym", 0x3, 0x0},
+ {"com_pad_ts1", 0x3, 0x1},
+ {"com_pad_ts2", 0x3, 0x2},
+ {"com_fts", 0x3, 0x3},
+ {"com_idl", 0x3, 0x4},
+ {"end_edb", 0x3, 0x5},
+ {"stp_sdp", 0x3, 0x6},
+ {"com_skp", 0x3, 0x7},
+ {"posted_tlp_hdr", 0x4, 0x0},
+ {"non_post_tlp_hdr", 0x4, 0x1},
+ {"cmpl_tlp_hdr", 0x4, 0x2},
+ {"posted_tlp_data", 0x4, 0x4},
+ {"non_post_tlp_data", 0x4, 0x5},
+ {"cmpl_tlp_data", 0x4, 0x6},
+ {"duplicate_dllp", 0x5, 0x0},
+ {"nullified_tlp", 0x5, 0x1},
+};
+
+static const u32 err_inj_type_mask[] = {
+ EINJ0_TYPE,
+ EINJ1_TYPE,
+ EINJ2_TYPE,
+ EINJ3_TYPE,
+ EINJ4_TYPE,
+ EINJ5_TYPE,
+};
+
static ssize_t lane_detect_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
struct dw_pcie *pci = file->private_data;
@@ -93,6 +173,63 @@ static ssize_t rx_valid_write(struct file *file, const char __user *buf, size_t
return lane_detect_write(file, buf, count, ppos);
}

+static ssize_t err_inj_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+ struct dwc_pcie_rasdes_priv *pdata = file->private_data;
+ struct dw_pcie *pci = pdata->pci;
+ struct dwc_pcie_rasdes_info *rinfo = pci->debugfs->rasdes_info;
+ u32 val, counter, vc_num, err_group, type_mask;
+ int val_diff = 0;
+ char *kern_buf;
+
+ err_group = err_inj_list[pdata->idx].err_inj_group;
+ type_mask = err_inj_type_mask[err_group];
+
+ kern_buf = memdup_user_nul(buf, count);
+ if (IS_ERR(kern_buf))
+ return PTR_ERR(kern_buf);
+
+ if (err_group == 4) {
+ val = sscanf(kern_buf, "%u %d %u", &counter, &val_diff, &vc_num);
+ if ((val != 3) || (val_diff < -4095 || val_diff > 4095)) {
+ kfree(kern_buf);
+ return -EINVAL;
+ }
+ } else if (err_group == 1) {
+ val = sscanf(kern_buf, "%u %d", &counter, &val_diff);
+ if ((val != 2) || (val_diff < -4095 || val_diff > 4095)) {
+ kfree(kern_buf);
+ return -EINVAL;
+ }
+ } else {
+ val = kstrtou32(kern_buf, 0, &counter);
+ if (val) {
+ kfree(kern_buf);
+ return val;
+ }
+ }
+
+ val = dw_pcie_readl_dbi(pci, rinfo->ras_cap_offset + ERR_INJ0_OFF + (0x4 * err_group));
+ val &= ~(type_mask | EINJ_COUNT);
+ val |= ((err_inj_list[pdata->idx].err_inj_type << EINJ_TYPE_SHIFT) & type_mask);
+ val |= FIELD_PREP(EINJ_COUNT, counter);
+
+ if (err_group == 1 || err_group == 4) {
+ val &= ~(EINJ_VAL_DIFF);
+ val |= FIELD_PREP(EINJ_VAL_DIFF, val_diff);
+ }
+ if (err_group == 4) {
+ val &= ~(EINJ_VC_NUM);
+ val |= FIELD_PREP(EINJ_VC_NUM, vc_num);
+ }
+
+ dw_pcie_writel_dbi(pci, rinfo->ras_cap_offset + ERR_INJ0_OFF + (0x4 * err_group), val);
+ dw_pcie_writel_dbi(pci, rinfo->ras_cap_offset + ERR_INJ_ENABLE_REG, (0x1 << err_group));
+
+ kfree(kern_buf);
+ return count;
+}
+
#define dwc_debugfs_create(name) \
debugfs_create_file(#name, 0644, rasdes_debug, pci, \
&dbg_ ## name ## _fops)
@@ -107,6 +244,11 @@ static const struct file_operations dbg_ ## name ## _fops = { \
DWC_DEBUGFS_FOPS(lane_detect);
DWC_DEBUGFS_FOPS(rx_valid);

+static const struct file_operations dwc_pcie_err_inj_ops = {
+ .open = simple_open,
+ .write = err_inj_write,
+};
+
static void dwc_pcie_rasdes_debugfs_deinit(struct dw_pcie *pci)
{
struct dwc_pcie_rasdes_info *rinfo = pci->debugfs->rasdes_info;
@@ -116,10 +258,11 @@ static void dwc_pcie_rasdes_debugfs_deinit(struct dw_pcie *pci)

static int dwc_pcie_rasdes_debugfs_init(struct dw_pcie *pci, struct dentry *dir)
{
- struct dentry *rasdes_debug;
+ struct dentry *rasdes_debug, *rasdes_err_inj;
struct dwc_pcie_rasdes_info *rasdes_info;
+ struct dwc_pcie_rasdes_priv *priv_tmp;
struct device *dev = pci->dev;
- int ras_cap;
+ int ras_cap, i, ret;

ras_cap = dw_pcie_find_rasdes_capability(pci);
if (!ras_cap) {
@@ -133,6 +276,7 @@ static int dwc_pcie_rasdes_debugfs_init(struct dw_pcie *pci, struct dentry *dir)

/* Create subdirectories for Debug, Error injection, Statistics */
rasdes_debug = debugfs_create_dir("rasdes_debug", dir);
+ rasdes_err_inj = debugfs_create_dir("rasdes_err_inj", dir);

mutex_init(&rasdes_info->reg_event_lock);
rasdes_info->ras_cap_offset = ras_cap;
@@ -142,7 +286,24 @@ static int dwc_pcie_rasdes_debugfs_init(struct dw_pcie *pci, struct dentry *dir)
dwc_debugfs_create(lane_detect);
dwc_debugfs_create(rx_valid);

+ /* Create debugfs files for Error injection subdirectory */
+ for (i = 0; i < ARRAY_SIZE(err_inj_list); i++) {
+ priv_tmp = devm_kzalloc(dev, sizeof(*priv_tmp), GFP_KERNEL);
+ if (!priv_tmp) {
+ ret = -ENOMEM;
+ goto err_deinit;
+ }
+
+ priv_tmp->idx = i;
+ priv_tmp->pci = pci;
+ debugfs_create_file(err_inj_list[i].name, 0200, rasdes_err_inj, priv_tmp,
+ &dwc_pcie_err_inj_ops);
+ }
return 0;
+
+err_deinit:
+ dwc_pcie_rasdes_debugfs_deinit(pci);
+ return ret;
}

void dwc_pcie_debugfs_deinit(struct dw_pcie *pci)
--
2.17.1