1 files changed, 86 insertions, 0 deletions

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index 8c354f946879..f1efe5beead6 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -13,6 +13,7 @@
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
+#include <linux/pm_runtime.h>
 #include <linux/soundwire/sdw_registers.h>
 #include <linux/soundwire/sdw.h>
 #include <sound/pcm_params.h>
@@ -50,6 +51,9 @@ MODULE_PARM_DESC(cdns_mcp_int_mask, "Cadence MCP IntMask");
 #define CDNS_MCP_CONTROL_BLOCK_WAKEUP		BIT(0)
 
 #define CDNS_MCP_CMDCTRL			0x8
+
+#define CDNS_MCP_CMDCTRL_INSERT_PARITY_ERR	BIT(2)
+
 #define CDNS_MCP_SSPSTAT			0xC
 #define CDNS_MCP_FRAME_SHAPE			0x10
 #define CDNS_MCP_FRAME_SHAPE_INIT		0x14
@@ -366,6 +370,85 @@ static int cdns_hw_reset(void *data, u64 value)
 
 DEFINE_DEBUGFS_ATTRIBUTE(cdns_hw_reset_fops, NULL, cdns_hw_reset, "%llu\n");
 
+static int cdns_parity_error_injection(void *data, u64 value)
+{
+	struct sdw_cdns *cdns = data;
+	struct sdw_bus *bus;
+	int ret;
+
+	if (value != 1)
+		return -EINVAL;
+
+	bus = &cdns->bus;
+
+	/*
+	 * Resume Master device. If this results in a bus reset, the
+	 * Slave devices will re-attach and be re-enumerated.
+	 */
+	ret = pm_runtime_get_sync(bus->dev);
+	if (ret < 0 && ret != -EACCES) {
+		dev_err_ratelimited(cdns->dev,
+				    "pm_runtime_get_sync failed in %s, ret %d\n",
+				    __func__, ret);
+		pm_runtime_put_noidle(bus->dev);
+		return ret;
+	}
+
+	/*
+	 * wait long enough for Slave(s) to be in steady state. This
+	 * does not need to be super precise.
+	 */
+	msleep(200);
+
+	/*
+	 * Take the bus lock here to make sure that any bus transactions
+	 * will be queued while we inject a parity error on a dummy read
+	 */
+	mutex_lock(&bus->bus_lock);
+
+	/* program hardware to inject parity error */
+	cdns_updatel(cdns, CDNS_MCP_CMDCTRL,
+		     CDNS_MCP_CMDCTRL_INSERT_PARITY_ERR,
+		     CDNS_MCP_CMDCTRL_INSERT_PARITY_ERR);
+
+	/* commit changes */
+	cdns_updatel(cdns, CDNS_MCP_CONFIG_UPDATE,
+		     CDNS_MCP_CONFIG_UPDATE_BIT,
+		     CDNS_MCP_CONFIG_UPDATE_BIT);
+
+	/* do a broadcast dummy read to avoid bus clashes */
+	ret = sdw_bread_no_pm_unlocked(&cdns->bus, 0xf, SDW_SCP_DEVID_0);
+	dev_info(cdns->dev, "parity error injection, read: %d\n", ret);
+
+	/* program hardware to disable parity error */
+	cdns_updatel(cdns, CDNS_MCP_CMDCTRL,
+		     CDNS_MCP_CMDCTRL_INSERT_PARITY_ERR,
+		     0);
+
+	/* commit changes */
+	cdns_updatel(cdns, CDNS_MCP_CONFIG_UPDATE,
+		     CDNS_MCP_CONFIG_UPDATE_BIT,
+		     CDNS_MCP_CONFIG_UPDATE_BIT);
+
+	/* Continue bus operation with parity error injection disabled */
+	mutex_unlock(&bus->bus_lock);
+
+	/* Userspace changed the hardware state behind the kernel's back */
+	add_taint(TAINT_USER, LOCKDEP_STILL_OK);
+
+	/*
+	 * allow Master device to enter pm_runtime suspend. This may
+	 * also result in Slave devices suspending.
+	 */
+	pm_runtime_mark_last_busy(bus->dev);
+	pm_runtime_put_autosuspend(bus->dev);
+
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(cdns_parity_error_fops, NULL,
+			 cdns_parity_error_injection, "%llu\n");
+
 /**
  * sdw_cdns_debugfs_init() - Cadence debugfs init
  * @cdns: Cadence instance
@@ -377,6 +460,9 @@ void sdw_cdns_debugfs_init(struct sdw_cdns *cdns, struct dentry *root)
 
 	debugfs_create_file("cdns-hw-reset", 0200, root, cdns,
 			    &cdns_hw_reset_fops);
+
+	debugfs_create_file("cdns-parity-error-injection", 0200, root, cdns,
+			    &cdns_parity_error_fops);
 }
 EXPORT_SYMBOL_GPL(sdw_cdns_debugfs_init);