[PATCH 03/10] PCI/ASPM: Use FIELD_GET()

Bjorn Helgaas
2023-10-10T20:44:58Z

From: Bjorn Helgaas <bhelgaas@google.com>

Add #defines for T_POWER_ON in the L1 PM Substates Capability and use
FIELD_PREP() and FIELD_GET() when possible. These remove the need for
explicit shifts. No functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/pci/pcie/aspm.c | 31 ++++++++++++++++++-------------
include/uapi/linux/pci_regs.h | 2 ++
2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 1bf630059264..06f175d8dee5 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -7,6 +7,7 @@
* Copyright (C) Shaohua Li (shaohua.li@intel.com)
*/

+#include <linux/bitfield.h>
#include <linux/kernel.h>
#include <linux/math.h>
#include <linux/module.h>
@@ -267,7 +268,7 @@ static void pcie_aspm_configure_common_clock(struct pcie_link_state *link)
/* Convert L0s latency encoding to ns */
static u32 calc_l0s_latency(u32 lnkcap)
{
- u32 encoding = (lnkcap & PCI_EXP_LNKCAP_L0SEL) >> 12;
+ u32 encoding = FIELD_GET(PCI_EXP_LNKCAP_L0SEL, lnkcap);

if (encoding == 0x7)
return (5 * 1000); /* > 4us */
@@ -285,7 +286,7 @@ static u32 calc_l0s_acceptable(u32 encoding)
/* Convert L1 latency encoding to ns */
static u32 calc_l1_latency(u32 lnkcap)
{
- u32 encoding = (lnkcap & PCI_EXP_LNKCAP_L1EL) >> 15;
+ u32 encoding = FIELD_GET(PCI_EXP_LNKCAP_L1EL, lnkcap);

if (encoding == 0x7)
return (65 * 1000); /* > 64us */
@@ -371,11 +372,11 @@ static void pcie_aspm_check_latency(struct pci_dev *endpoint)
link = endpoint->bus->self->link_state;

/* Calculate endpoint L0s acceptable latency */
- encoding = (endpoint->devcap & PCI_EXP_DEVCAP_L0S) >> 6;
+ encoding = FIELD_GET(PCI_EXP_DEVCAP_L0S, endpoint->devcap);
acceptable_l0s = calc_l0s_acceptable(encoding);

/* Calculate endpoint L1 acceptable latency */
- encoding = (endpoint->devcap & PCI_EXP_DEVCAP_L1) >> 9;
+ encoding = FIELD_GET(PCI_EXP_DEVCAP_L1, endpoint->devcap);
acceptable_l1 = calc_l1_acceptable(encoding);

while (link) {
@@ -446,22 +447,24 @@ static void aspm_calc_l12_info(struct pcie_link_state *link,
u32 pl1_2_enables, cl1_2_enables;

/* Choose the greater of the two Port Common_Mode_Restore_Times */
- val1 = (parent_l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
- val2 = (child_l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
+ val1 = FIELD_GET(PCI_L1SS_CAP_CM_RESTORE_TIME, parent_l1ss_cap);
+ val2 = FIELD_GET(PCI_L1SS_CAP_CM_RESTORE_TIME, child_l1ss_cap);
t_common_mode = max(val1, val2);

/* Choose the greater of the two Port T_POWER_ON times */
- val1 = (parent_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
- scale1 = (parent_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
- val2 = (child_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
- scale2 = (child_l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
+ val1 = FIELD_GET(PCI_L1SS_CAP_P_PWR_ON_VALUE, parent_l1ss_cap);
+ scale1 = FIELD_GET(PCI_L1SS_CAP_P_PWR_ON_SCALE, parent_l1ss_cap);
+ val2 = FIELD_GET(PCI_L1SS_CAP_P_PWR_ON_VALUE, child_l1ss_cap);
+ scale2 = FIELD_GET(PCI_L1SS_CAP_P_PWR_ON_SCALE, child_l1ss_cap);

if (calc_l12_pwron(parent, scale1, val1) >
calc_l12_pwron(child, scale2, val2)) {
- ctl2 |= scale1 | (val1 << 3);
+ ctl2 |= FIELD_PREP(PCI_L1SS_CTL2_T_PWR_ON_SCALE, scale1) |
+ FIELD_PREP(PCI_L1SS_CTL2_T_PWR_ON_VALUE, val1);
t_power_on = calc_l12_pwron(parent, scale1, val1);
} else {
- ctl2 |= scale2 | (val2 << 3);
+ ctl2 |= FIELD_PREP(PCI_L1SS_CTL2_T_PWR_ON_SCALE, scale2) |
+ FIELD_PREP(PCI_L1SS_CTL2_T_PWR_ON_VALUE, val2);
t_power_on = calc_l12_pwron(child, scale2, val2);
}

@@ -477,7 +480,9 @@ static void aspm_calc_l12_info(struct pcie_link_state *link,
*/
l1_2_threshold = 2 + 4 + t_common_mode + t_power_on;
encode_l12_threshold(l1_2_threshold, &scale, &value);
- ctl1 |= t_common_mode << 8 | scale << 29 | value << 16;
+ ctl1 |= FIELD_PREP(PCI_L1SS_CTL1_CM_RESTORE_TIME, t_common_mode) |
+ FIELD_PREP(PCI_L1SS_CTL1_LTR_L12_TH_VALUE, value) |
+ FIELD_PREP(PCI_L1SS_CTL1_LTR_L12_TH_SCALE, scale);

/* Some broken devices only support dword access to L1 SS */
pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1, &pctl1);
diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index e5f558d96493..34bf037993f3 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -1088,6 +1088,8 @@
#define PCI_L1SS_CTL1_LTR_L12_TH_VALUE 0x03ff0000 /* LTR_L1.2_THRESHOLD_Value */
#define PCI_L1SS_CTL1_LTR_L12_TH_SCALE 0xe0000000 /* LTR_L1.2_THRESHOLD_Scale */
#define PCI_L1SS_CTL2 0x0c /* Control 2 Register */
+#define PCI_L1SS_CTL2_T_PWR_ON_SCALE 0x00000003 /* T_POWER_ON Scale */
+#define PCI_L1SS_CTL2_T_PWR_ON_VALUE 0x000000f8 /* T_POWER_ON Value */

/* Designated Vendor-Specific (DVSEC, PCI_EXT_CAP_ID_DVSEC) */
#define PCI_DVSEC_HEADER1 0x4 /* Designated Vendor-Specific Header1 */
--
2.34.1