[PATCH v2 0/6] Improve link speed presentation process

[PATCH v2 0/6] Improve link speed presentation process

[Yicong Yang]

In this series:
1. Add 32 GT/s decoding in some macros as a complementary
2. Remove redundancy in speed presentation process and improve the codes.

Currently We use switch-case statements to acquire the speed
string according to the pci bus speed in current_link_speed_show()
and pcie_get_speed_cap(). It leads to redundant and when new
standard comes, we have to add cases in the related functions,
which is easy to omit at somewhere.

Abstract the judge statements out. Use macros and pci speed
arrays instead. Then only the macros and arrays need to be
extended when next generation comes.

Link:
https://lore.kernel.org/linux-pci/20200113211728.GA113776@google.com/
https://lore.kernel.org/linux-pci/20200114224909.GA19633@google.com/

change since v1:
1. split "PCI: Make pci_bus_speed_strings[] public" from the series
2. split v1 PATCH 4 to two patches as suggested
3. modify some description in commit as suggested

Yicong Yang (6):
  PCI: add 32 GT/s decoding in some macros
  PCI: Add comments for link speed info arrays
  PCI: Refactor and rename PCIE_SPEED2STR macro
  PCI: Refactor bus_speed_read() with PCI_SPEED2STR macro
  PCI: Add PCIE_LNKCAP2_SLS2SPEED macro
  PCI: Reduce redundancy in current_link_speed_show()

 drivers/pci/pci-sysfs.c | 26 ++++----------------------
 drivers/pci/pci.c       | 23 +++++++----------------
 drivers/pci/pci.h       | 21 ++++++++++++++-------
 drivers/pci/probe.c     |  8 ++++++++
 drivers/pci/slot.c      | 10 +++-------
 5 files changed, 36 insertions(+), 52 deletions(-)

--
2.8.1

[PATCH v2 1/6] PCI: add 32 GT/s decoding in some macros

[Yicong Yang]

Link speed 32.0 GT/s is supported in PCIe r5.0. Add in macro
PCIE_SPEED2STR and PCIE_SPEED2MBS_ENC to correctly decode.
This patch is a complementary to
commit de76cda215d5 ("PCI: Decode PCIe 32 GT/s link speed").

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/pci/pci.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index e6bcc06..d2e92b0f 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -296,7 +296,8 @@ void pci_bus_put(struct pci_bus *bus);
 
 /* PCIe link information */
 #define PCIE_SPEED2STR(speed) \
-	((speed) == PCIE_SPEED_16_0GT ? "16 GT/s" : \
+	((speed) == PCIE_SPEED_32_0GT ? "32 GT/s" : \
+	 (speed) == PCIE_SPEED_16_0GT ? "16 GT/s" : \
 	 (speed) == PCIE_SPEED_8_0GT ? "8 GT/s" : \
 	 (speed) == PCIE_SPEED_5_0GT ? "5 GT/s" : \
 	 (speed) == PCIE_SPEED_2_5GT ? "2.5 GT/s" : \
@@ -304,7 +305,8 @@ void pci_bus_put(struct pci_bus *bus);
 
 /* PCIe speed to Mb/s reduced by encoding overhead */
 #define PCIE_SPEED2MBS_ENC(speed) \
-	((speed) == PCIE_SPEED_16_0GT ? 16000*128/130 : \
+	((speed) == PCIE_SPEED_32_0GT ? 32000*128/130 : \
+	 (speed) == PCIE_SPEED_16_0GT ? 16000*128/130 : \
 	 (speed) == PCIE_SPEED_8_0GT  ?  8000*128/130 : \
 	 (speed) == PCIE_SPEED_5_0GT  ?  5000*8/10 : \
 	 (speed) == PCIE_SPEED_2_5GT  ?  2500*8/10 : \
-- 
2.8.1

[PATCH v2 2/6] PCI: Add comments for link speed info arrays

[Yicong Yang]

Add comments for pcix_bus_speed[] and pcie_link_speed[] arrays.
Indicating the capabilities which the information from.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/pci/probe.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 6ce47d8..84b012f 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -640,6 +640,10 @@ void pci_free_host_bridge(struct pci_host_bridge *bridge)
 }
 EXPORT_SYMBOL(pci_free_host_bridge);
 
+/**
+ * these indices represent secondary bus mode and
+ * frequency from  PCI_X_SSTATUS_FREQ
+ **/
 static const unsigned char pcix_bus_speed[] = {
 	PCI_SPEED_UNKNOWN,		/* 0 */
 	PCI_SPEED_66MHz_PCIX,		/* 1 */
@@ -659,6 +663,10 @@ static const unsigned char pcix_bus_speed[] = {
 	PCI_SPEED_133MHz_PCIX_533	/* F */
 };
 
+/**
+ * these indices represent PCIe link speed from
+ * PCI_EXP_LNKCAP, PCI_EXP_LNKSTA, PCI_EXP_LNKCAP2
+ **/
 const unsigned char pcie_link_speed[] = {
 	PCI_SPEED_UNKNOWN,		/* 0 */
 	PCIE_SPEED_2_5GT,		/* 1 */
-- 
2.8.1

[PATCH v2 3/6] PCI: Refactor and rename PCIE_SPEED2STR macro

[Yicong Yang]

Use pci_bus_speed_strings[] array to refactor PCIE_SPEED2STR
macro. Rename it with PCI_SPEED2STR as it can also used to
decode non-PCIe speeds with pci_bus_speed_strings[].

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/pci/pci-sysfs.c |  2 +-
 drivers/pci/pci.c       |  6 +++---
 drivers/pci/pci.h       | 10 +++-------
 3 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 13f766d..f4eafbc 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -156,7 +156,7 @@ static ssize_t max_link_speed_show(struct device *dev,
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 
-	return sprintf(buf, "%s\n", PCIE_SPEED2STR(pcie_get_speed_cap(pdev)));
+	return sprintf(buf, "%s\n", PCI_SPEED2STR(pcie_get_speed_cap(pdev)));
 }
 static DEVICE_ATTR_RO(max_link_speed);
 
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 3c30e72..7285fe0 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5871,14 +5871,14 @@ void __pcie_print_link_status(struct pci_dev *dev, bool verbose)
 	if (bw_avail >= bw_cap && verbose)
 		pci_info(dev, "%u.%03u Gb/s available PCIe bandwidth (%s x%d link)\n",
 			 bw_cap / 1000, bw_cap % 1000,
-			 PCIE_SPEED2STR(speed_cap), width_cap);
+			 PCI_SPEED2STR(speed_cap), width_cap);
 	else if (bw_avail < bw_cap)
 		pci_info(dev, "%u.%03u Gb/s available PCIe bandwidth, limited by %s x%d link at %s (capable of %u.%03u Gb/s with %s x%d link)\n",
 			 bw_avail / 1000, bw_avail % 1000,
-			 PCIE_SPEED2STR(speed), width,
+			 PCI_SPEED2STR(speed), width,
 			 limiting_dev ? pci_name(limiting_dev) : "<unknown>",
 			 bw_cap / 1000, bw_cap % 1000,
-			 PCIE_SPEED2STR(speed_cap), width_cap);
+			 PCI_SPEED2STR(speed_cap), width_cap);
 }
 
 /**
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index d2e92b0f..ba6b2cb 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -295,13 +295,9 @@ struct pci_bus *pci_bus_get(struct pci_bus *bus);
 void pci_bus_put(struct pci_bus *bus);
 
 /* PCIe link information */
-#define PCIE_SPEED2STR(speed) \
-	((speed) == PCIE_SPEED_32_0GT ? "32 GT/s" : \
-	 (speed) == PCIE_SPEED_16_0GT ? "16 GT/s" : \
-	 (speed) == PCIE_SPEED_8_0GT ? "8 GT/s" : \
-	 (speed) == PCIE_SPEED_5_0GT ? "5 GT/s" : \
-	 (speed) == PCIE_SPEED_2_5GT ? "2.5 GT/s" : \
-	 "Unknown speed")
+#define PCI_SPEED2STR(speed) \
+	((speed) < pci_bus_speed_strings_size ? \
+	 pci_bus_speed_strings[speed] : "Unknown speed")
 
 /* PCIe speed to Mb/s reduced by encoding overhead */
 #define PCIE_SPEED2MBS_ENC(speed) \
-- 
2.8.1

[PATCH v2 4/6] PCI: Refactor bus_speed_read() with PCI_SPEED2STR macro

[Yicong Yang]

Use PCI_SPEED2STR macro to replace judgement statment in
bus_speed_read() function. Add "PCIe" suffix when decoding PCIe
speed for proper display.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/pci/slot.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c
index fb7c172..871d598 100644
--- a/drivers/pci/slot.c
+++ b/drivers/pci/slot.c
@@ -51,14 +51,10 @@ static ssize_t address_read_file(struct pci_slot *slot, char *buf)
 
 static ssize_t bus_speed_read(enum pci_bus_speed speed, char *buf)
 {
-	const char *speed_string;
+	if (speed <= PCI_SPEED_133MHz_PCIX_533)
+		return sprintf(buf, "%s\n", PCI_SPEED2STR(speed));
 
-	if (speed < pci_bus_speed_strings_size)
-		speed_string = pci_bus_speed_strings[speed];
-	else
-		speed_string = "Unknown";
-
-	return sprintf(buf, "%s\n", speed_string);
+	return sprintf(buf, "%s PCIe\n", PCI_SPEED2STR(speed));
 }
 
 static ssize_t max_speed_read_file(struct pci_slot *slot, char *buf)
-- 
2.8.1

[PATCH v2 5/6] PCI: Add PCIE_LNKCAP2_SLS2SPEED macro

[Yicong Yang]

Add PCIE_LNKCAP2_SLS2SPEED macro for transforming raw link cap 2
value to link speed. Use it in pcie_get_speed_cap() to replace
judgement statements. Then we don't need to touch the functions
when new link speed comes.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/pci/pci.c | 17 ++++-------------
 drivers/pci/pci.h |  9 +++++++++
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 7285fe0..99f34d5 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5783,19 +5783,10 @@ enum pci_bus_speed pcie_get_speed_cap(struct pci_dev *dev)
 	 * where only 2.5 GT/s and 5.0 GT/s speeds were defined.
 	 */
 	pcie_capability_read_dword(dev, PCI_EXP_LNKCAP2, &lnkcap2);
-	if (lnkcap2) { /* PCIe r3.0-compliant */
-		if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_32_0GB)
-			return PCIE_SPEED_32_0GT;
-		else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_16_0GB)
-			return PCIE_SPEED_16_0GT;
-		else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_8_0GB)
-			return PCIE_SPEED_8_0GT;
-		else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_5_0GB)
-			return PCIE_SPEED_5_0GT;
-		else if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_2_5GB)
-			return PCIE_SPEED_2_5GT;
-		return PCI_SPEED_UNKNOWN;
-	}
+
+	/* PCIe r3.0-compliant */
+	if (lnkcap2)
+		return PCIE_LNKCAP2_SLS2SPEED(lnkcap2);
 
 	pcie_capability_read_dword(dev, PCI_EXP_LNKCAP, &lnkcap);
 	if ((lnkcap & PCI_EXP_LNKCAP_SLS) == PCI_EXP_LNKCAP_SLS_5_0GB)
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index ba6b2cb..7651749 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -299,6 +299,15 @@ void pci_bus_put(struct pci_bus *bus);
 	((speed) < pci_bus_speed_strings_size ? \
 	 pci_bus_speed_strings[speed] : "Unknown speed")
 
+/* PCIe link information from Link Capabilities 2 */
+#define PCIE_LNKCAP2_SLS2SPEED(lnkcap2) \
+	((lnkcap2) & PCI_EXP_LNKCAP2_SLS_32_0GB ? PCIE_SPEED_32_0GT : \
+	 (lnkcap2) & PCI_EXP_LNKCAP2_SLS_16_0GB ? PCIE_SPEED_16_0GT : \
+	 (lnkcap2) & PCI_EXP_LNKCAP2_SLS_8_0GB ? PCIE_SPEED_8_0GT : \
+	 (lnkcap2) & PCI_EXP_LNKCAP2_SLS_5_0GB ? PCIE_SPEED_5_0GT : \
+	 (lnkcap2) & PCI_EXP_LNKCAP2_SLS_2_5GB ? PCIE_SPEED_2_5GT : \
+	 PCI_SPEED_UNKNOWN)
+
 /* PCIe speed to Mb/s reduced by encoding overhead */
 #define PCIE_SPEED2MBS_ENC(speed) \
 	((speed) == PCIE_SPEED_32_0GT ? 32000*128/130 : \
-- 
2.8.1

[PATCH v2 6/6] PCI: Reduce redundancy in current_link_speed_show()

[Yicong Yang]

Remove switch-case statements in current_link_speed_show(). Use
pcie_link_speed[] array to get link speed and PCI_SPEED2STR macro
to get link speed string.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/pci/pci-sysfs.c | 24 +++---------------------
 1 file changed, 3 insertions(+), 21 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index f4eafbc..eaece10 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -175,33 +175,15 @@ static ssize_t current_link_speed_show(struct device *dev,
 	struct pci_dev *pci_dev = to_pci_dev(dev);
 	u16 linkstat;
 	int err;
-	const char *speed;
+	enum pci_bus_speed speed;
 
 	err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);
 	if (err)
 		return -EINVAL;
 
-	switch (linkstat & PCI_EXP_LNKSTA_CLS) {
-	case PCI_EXP_LNKSTA_CLS_32_0GB:
-		speed = "32 GT/s";
-		break;
-	case PCI_EXP_LNKSTA_CLS_16_0GB:
-		speed = "16 GT/s";
-		break;
-	case PCI_EXP_LNKSTA_CLS_8_0GB:
-		speed = "8 GT/s";
-		break;
-	case PCI_EXP_LNKSTA_CLS_5_0GB:
-		speed = "5 GT/s";
-		break;
-	case PCI_EXP_LNKSTA_CLS_2_5GB:
-		speed = "2.5 GT/s";
-		break;
-	default:
-		speed = "Unknown speed";
-	}
+	speed = pcie_link_speed[linkstat & PCI_EXP_LNKSTA_CLS];
 
-	return sprintf(buf, "%s\n", speed);
+	return sprintf(buf, "%s\n", PCI_SPEED2STR(speed));
 }
 static DEVICE_ATTR_RO(current_link_speed);
 
-- 
2.8.1