aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorNiklas Neronin <niklas.neronin@linux.intel.com>2025-11-19 16:24:12 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2025-11-21 14:53:01 +0100
commitedab00902be0001b65be934ce3e748fcc36cc220 (patch)
tree2b15f392d3d275cca88c9923ab8e8b1611adb8d5
parent8e9a3a1ea1b6e95e4503b258e7d6b1c4790c2e82 (diff)
downloadtip-edab00902be0001b65be934ce3e748fcc36cc220.tar.gz
usb: xhci: improve xhci-caps.h comments
No functional changes. This patch updates comments in xhci-caps.h for better readability and consistency. Each Capability Register bit field now includes a brief description of its name and valid range, following a uniform comment format across the file. These updates are based on the xHCI specification, revision 1.2. Bit field comment format: /* <bit range> - <Field name>,<noteworthy information if any> */ Why print the bit range? The bit range aids in identifying missing macros and reserved bit ranges. Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Link: https://patch.msgid.link/20251119142417.2820519-19-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat
-rw-r--r--drivers/usb/host/xhci-caps.h100
1 files changed, 57 insertions, 43 deletions
diff --git a/drivers/usb/host/xhci-caps.h b/drivers/usb/host/xhci-caps.h
index 8390c969389e3e..8a435786f950f6 100644
--- a/drivers/usb/host/xhci-caps.h
+++ b/drivers/usb/host/xhci-caps.h
@@ -1,93 +1,107 @@
/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * xHCI Host Controller Capability Registers.
+ * xHCI Specification Section 5.3, Revision 1.2.
+ */
-/* hc_capbase bitmasks */
-/* bits 7:0 - how long is the Capabilities register */
+/* hc_capbase - bitmasks */
+/* bits 7:0 - Capability Registers Length */
#define HC_LENGTH(p) XHCI_HC_LENGTH(p)
-/* bits 31:16 */
+/* bits 15:8 - Rsvd */
+/* bits 31:16 - Host Controller Interface Version Number */
#define HC_VERSION(p) (((p) >> 16) & 0xffff)
/* HCSPARAMS1 - hcs_params1 - bitmasks */
-/* bits 0:7, Max Device Slots */
+/* bits 7:0 - Number of Device Slots */
#define HCS_MAX_SLOTS(p) (((p) >> 0) & 0xff)
#define HCS_SLOTS_MASK 0xff
-/* bits 8:18, Max Interrupters */
+/* bits 18:8 - Number of Interrupters, max values is 1024 */
#define HCS_MAX_INTRS(p) (((p) >> 8) & 0x7ff)
/* bits 31:24, Max Ports - max value is 255 */
#define HCS_MAX_PORTS(p) (((p) >> 24) & 0xff)
/* HCSPARAMS2 - hcs_params2 - bitmasks */
-/* bits 0:3, frames or uframes that SW needs to queue transactions
- * ahead of the HW to meet periodic deadlines */
+/*
+ * bits 3:0 - Isochronous Scheduling Threshold, frames or uframes that SW
+ * needs to queue transactions ahead of the HW to meet periodic deadlines.
+ */
#define HCS_IST(p) (((p) >> 0) & 0xf)
-/* bits 4:7, max number of Event Ring segments */
+/* bits 7:4 - Event Ring Segment Table Max, 2^(n) */
#define HCS_ERST_MAX(p) (((p) >> 4) & 0xf)
-/* bits 21:25 Hi 5 bits of Scratchpad buffers SW must allocate for the HW */
-/* bit 26 Scratchpad restore - for save/restore HW state - not used yet */
-/* bits 27:31 Lo 5 bits of Scratchpad buffers SW must allocate for the HW */
+/* bits 20:8 - Rsvd */
+/* bits 25:21 - Max Scratchpad Buffers (Hi), 5 Most significant bits */
+/* bit 26 - Scratchpad restore, for save/restore HW state */
+/* bits 31:27 - Max Scratchpad Buffers (Lo), 5 Least significant bits */
#define HCS_MAX_SCRATCHPAD(p) ((((p) >> 16) & 0x3e0) | (((p) >> 27) & 0x1f))
/* HCSPARAMS3 - hcs_params3 - bitmasks */
-/* bits 0:7, Max U1 to U0 latency for the roothub ports */
+/* bits 7:0 - U1 Device Exit Latency, Max U1 to U0 latency for the roothub ports */
#define HCS_U1_LATENCY(p) (((p) >> 0) & 0xff)
-/* bits 16:31, Max U2 to U0 latency for the roothub ports */
+/* bits 15:8 - Rsvd */
+/* bits 31:16 - U2 Device Exit Latency, Max U2 to U0 latency for the roothub ports */
#define HCS_U2_LATENCY(p) (((p) >> 16) & 0xffff)
-/* HCCPARAMS - hcc_params - bitmasks */
-/* true: HC can use 64-bit address pointers */
+/* HCCPARAMS1 - hcc_params - bitmasks */
+/* bit 0 - 64-bit Addressing Capability */
#define HCC_64BIT_ADDR(p) ((p) & (1 << 0))
-/* true: HC can do bandwidth negotiation */
+/* bit 1 - BW Negotiation Capability */
#define HCC_BANDWIDTH_NEG(p) ((p) & (1 << 1))
-/* true: HC uses 64-byte Device Context structures
- * FIXME 64-byte context structures aren't supported yet.
- */
+/* bit 2 - Context Size */
#define HCC_64BYTE_CONTEXT(p) ((p) & (1 << 2))
-/* true: HC has port power switches */
+#define CTX_SIZE(_hcc) (HCC_64BYTE_CONTEXT(_hcc) ? 64 : 32)
+/* bit 3 - Port Power Control */
#define HCC_PPC(p) ((p) & (1 << 3))
-/* true: HC has port indicators */
+/* bit 4 - Port Indicators */
#define HCS_INDICATOR(p) ((p) & (1 << 4))
-/* true: HC has Light HC Reset Capability */
+/* bit 5 - Light HC Reset Capability */
#define HCC_LIGHT_RESET(p) ((p) & (1 << 5))
-/* true: HC supports latency tolerance messaging */
+/* bit 6 - Latency Tolerance Messaging Capability */
#define HCC_LTC(p) ((p) & (1 << 6))
-/* true: no secondary Stream ID Support */
+/* bit 7 - No Secondary Stream ID Support */
#define HCC_NSS(p) ((p) & (1 << 7))
-/* true: HC supports Stopped - Short Packet */
+/* bit 8 - Parse All Event Data */
+/* bit 9 - Short Packet Capability */
#define HCC_SPC(p) ((p) & (1 << 9))
-/* true: HC has Contiguous Frame ID Capability */
+/* bit 10 - Stopped EDTLA Capability */
+/* bit 11 - Contiguous Frame ID Capability */
#define HCC_CFC(p) ((p) & (1 << 11))
-/* Max size for Primary Stream Arrays - 2^(n+1), where n is bits 12:15 */
+/* bits 15:12 - Max size for Primary Stream Arrays, 2^(n+1) */
#define HCC_MAX_PSA(p) (1 << ((((p) >> 12) & 0xf) + 1))
-/* Extended Capabilities pointer from PCI base - section 5.3.6 */
+/* bits 31:16 - xHCI Extended Capabilities Pointer, from PCI base: 2^(n) */
#define HCC_EXT_CAPS(p) XHCI_HCC_EXT_CAPS(p)
-#define CTX_SIZE(_hcc) (HCC_64BYTE_CONTEXT(_hcc) ? 64 : 32)
-
-/* db_off bitmask - bits 31:2 Doorbell Array Offset */
+/* DBOFF - db_off - bitmasks */
+/* bits 1:0 - Rsvd */
+/* bits 31:2 - Doorbell Array Offset */
#define DBOFF_MASK (0xfffffffc)
-/* run_regs_off bitmask - bits 0:4 reserved */
+/* RTSOFF - run_regs_off - bitmasks */
+/* bits 4:0 - Rsvd */
+/* bits 31:5 - Runtime Register Space Offse */
#define RTSOFF_MASK (~0x1f)
/* HCCPARAMS2 - hcc_params2 - bitmasks */
-/* true: HC supports U3 entry Capability */
+/* bit 0 - U3 Entry Capability */
#define HCC2_U3C(p) ((p) & (1 << 0))
-/* true: HC supports Configure endpoint command Max exit latency too large */
+/* bit 1 - Configure Endpoint Command Max Exit Latency Too Large Capability */
#define HCC2_CMC(p) ((p) & (1 << 1))
-/* true: HC supports Force Save context Capability */
+/* bit 2 - Force Save Context Capabilitu */
#define HCC2_FSC(p) ((p) & (1 << 2))
-/* true: HC supports Compliance Transition Capability */
+/* bit 3 - Compliance Transition Capability, false: compliance is enabled by default */
#define HCC2_CTC(p) ((p) & (1 << 3))
-/* true: HC support Large ESIT payload Capability > 48k */
+/* bit 4 - Large ESIT Payload Capability, true: HC support ESIT payload > 48k */
#define HCC2_LEC(p) ((p) & (1 << 4))
-/* true: HC support Configuration Information Capability */
+/* bit 5 - Configuration Information Capability */
#define HCC2_CIC(p) ((p) & (1 << 5))
-/* true: HC support Extended TBC Capability, Isoc burst count > 65535 */
+/* bit 6 - Extended TBC Capability, true: Isoc burst count > 65535 */
#define HCC2_ETC(p) ((p) & (1 << 6))
-/* true: HC support Extended TBC TRB Status Capability */
+/* bit 7 - Extended TBC TRB Status Capability */
#define HCC2_ETC_TSC(p) ((p) & (1 << 7))
-/* true: HC support Get/Set Extended Property Capability */
+/* bit 8 - Get/Set Extended Property Capability */
#define HCC2_GSC(p) ((p) & (1 << 8))
-/* true: HC support Virtualization Based Trusted I/O Capability */
+/* bit 9 - Virtualization Based Trusted I/O Capability */
#define HCC2_VTC(p) ((p) & (1 << 9))
-/* true: HC support Double BW on a eUSB2 HS ISOC EP */
+/* bit 10 - Rsvd */
+/* bit 11 - HC support Double BW on a eUSB2 HS ISOC EP */
#define HCC2_EUSB2_DIC(p) ((p) & (1 << 11))
+/* bits 31:12 - Rsvd */
generated by cgit 1.2.3-korg (git 2.43.0) at 2025-12-12 19:18:22 +0000