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

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

[Rajat Khandelwal]

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@linux.intel.com>
---

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

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

[Greg KH]

On Wed, Apr 19, 2023 at 06:33:45PM +0530, Rajat Khandelwal wrote:
> 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@linux.intel.com>
> ---
> 
> v3: Allocate the debugfs directory name for the platform device with
> its ACPI dev name included

{sigh}   No, sorry, this is not correct.

Also, you did not properly follow the rules that all Intel kernel
developers are supposed to follow.  Please consult your local kernel
developer team and do so before sending any more kernel patches out.

greg k-h