[PATCH v3] usb: typec: intel_pmc_mux: Expose IOM port status to debugfs

[Rajat Khandelwal <rajat.khandelwal@xxxxxxxxxxxxxxx>]

IOM status has a crucial role during debugging to check the
current state of the type-C port.
There are ways to fetch the status, but all those require the
IOM port status offset, which could change with platform.

Make a debugfs directory for intel_pmc_mux and expose the status
under it per port basis.

Signed-off-by: Rajat Khandelwal <rajat.khandelwal@xxxxxxxxxxxxxxx>
---

v3: Allocate the debugfs directory name for the platform device with
its ACPI dev name included

v2:
1. Remove static declaration of the debugfs root for 'intel_pmc_mux'
2. Remove explicitly defined one-liner functions

 drivers/usb/typec/mux/intel_pmc_mux.c | 38 +++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/usb/typec/mux/intel_pmc_mux.c b/drivers/usb/typec/mux/intel_pmc_mux.c
index 34e4188a40ff..2264b8dd5436 100644
--- a/drivers/usb/typec/mux/intel_pmc_mux.c
+++ b/drivers/usb/typec/mux/intel_pmc_mux.c
@@ -15,6 +15,7 @@
 #include <linux/usb/typec_mux.h>
 #include <linux/usb/typec_dp.h>
 #include <linux/usb/typec_tbt.h>
+#include <linux/debugfs.h>
 
 #include <asm/intel_scu_ipc.h>
 
@@ -143,6 +144,10 @@ struct pmc_usb {
 	struct acpi_device *iom_adev;
 	void __iomem *iom_base;
 	u32 iom_port_status_offset;
+
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *dentry;
+#endif
 };
 
 static void update_port_status(struct pmc_usb_port *port)
@@ -639,10 +644,34 @@ static int pmc_usb_probe_iom(struct pmc_usb *pmc)
 	return 0;
 }
 
+static int port_iom_status_show(struct seq_file *s, void *unused)
+{
+	struct pmc_usb_port *port = s->private;
+
+	update_port_status(port);
+	seq_printf(s, "0x%08x\n", port->iom_status);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(port_iom_status);
+
+static void pmc_mux_port_debugfs_init(struct pmc_usb_port *port)
+{
+	struct dentry *debugfs_dir;
+	char name[6];
+
+	snprintf(name, sizeof(name), "port%d", port->usb3_port - 1);
+
+	debugfs_dir = debugfs_create_dir(name, port->pmc->dentry);
+	debugfs_create_file("iom_status", 0400, debugfs_dir, port,
+			    &port_iom_status_fops);
+}
+
 static int pmc_usb_probe(struct platform_device *pdev)
 {
 	struct fwnode_handle *fwnode = NULL;
 	struct pmc_usb *pmc;
+	char name[NAME_MAX];
 	int i = 0;
 	int ret;
 
@@ -674,6 +703,9 @@ static int pmc_usb_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	snprintf(name, NAME_MAX, "intel_pmc_mux-%s", pdev->name);
+	pmc->dentry = debugfs_create_dir(name, NULL);
+
 	/*
 	 * For every physical USB connector (USB2 and USB3 combo) there is a
 	 * child ACPI device node under the PMC mux ACPI device object.
@@ -688,6 +720,8 @@ static int pmc_usb_probe(struct platform_device *pdev)
 			fwnode_handle_put(fwnode);
 			goto err_remove_ports;
 		}
+
+		pmc_mux_port_debugfs_init(&pmc->port[i]);
 	}
 
 	platform_set_drvdata(pdev, pmc);
@@ -703,6 +737,8 @@ static int pmc_usb_probe(struct platform_device *pdev)
 
 	acpi_dev_put(pmc->iom_adev);
 
+	debugfs_remove(pmc->dentry);
+
 	return ret;
 }
 
@@ -719,6 +755,8 @@ static int pmc_usb_remove(struct platform_device *pdev)
 
 	acpi_dev_put(pmc->iom_adev);
 
+	debugfs_remove(pmc->dentry);
+
 	return 0;
 }
 
-- 
2.34.1