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PCI: mvebu: Add support for sending Set_Slot_Power_Limit message
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If DT supplies the 'slot-power-limit-milliwatt' property, program
the value in the Slot Power Limit in the Slot Capabilities register
and program the Root Port to send a Set_Slot_Power_Limit Message
when the Link transitions to DL_Up.

Link: https://lore.kernel.org/r/20220412094946.27069-5-pali@kernel.org
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
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Pali Rohár authored and Lorenzo Pieralisi committed Apr 25, 2022
1 parent 3566242 commit 0d5b8c2
Showing 1 changed file with 92 additions and 5 deletions.
97 changes: 92 additions & 5 deletions drivers/pci/controller/pci-mvebu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/gpio.h>
Expand Down Expand Up @@ -66,6 +67,12 @@
#define PCIE_STAT_BUS 0xff00
#define PCIE_STAT_DEV 0x1f0000
#define PCIE_STAT_LINK_DOWN BIT(0)
#define PCIE_SSPL_OFF 0x1a0c
#define PCIE_SSPL_VALUE_SHIFT 0
#define PCIE_SSPL_VALUE_MASK GENMASK(7, 0)
#define PCIE_SSPL_SCALE_SHIFT 8
#define PCIE_SSPL_SCALE_MASK GENMASK(9, 8)
#define PCIE_SSPL_ENABLE BIT(16)
#define PCIE_RC_RTSTA 0x1a14
#define PCIE_DEBUG_CTRL 0x1a60
#define PCIE_DEBUG_SOFT_RESET BIT(20)
Expand Down Expand Up @@ -111,6 +118,8 @@ struct mvebu_pcie_port {
struct mvebu_pcie_window iowin;
u32 saved_pcie_stat;
struct resource regs;
u8 slot_power_limit_value;
u8 slot_power_limit_scale;
struct irq_domain *intx_irq_domain;
raw_spinlock_t irq_lock;
int intx_irq;
Expand Down Expand Up @@ -239,7 +248,7 @@ static void mvebu_pcie_setup_wins(struct mvebu_pcie_port *port)

static void mvebu_pcie_setup_hw(struct mvebu_pcie_port *port)
{
u32 ctrl, lnkcap, cmd, dev_rev, unmask;
u32 ctrl, lnkcap, cmd, dev_rev, unmask, sspl;

/* Setup PCIe controller to Root Complex mode. */
ctrl = mvebu_readl(port, PCIE_CTRL_OFF);
Expand Down Expand Up @@ -292,6 +301,20 @@ static void mvebu_pcie_setup_hw(struct mvebu_pcie_port *port)
/* Point PCIe unit MBUS decode windows to DRAM space. */
mvebu_pcie_setup_wins(port);

/*
* Program Root Port to automatically send Set_Slot_Power_Limit
* PCIe Message when changing status from Dl_Down to Dl_Up and valid
* slot power limit was specified.
*/
sspl = mvebu_readl(port, PCIE_SSPL_OFF);
sspl &= ~(PCIE_SSPL_VALUE_MASK | PCIE_SSPL_SCALE_MASK | PCIE_SSPL_ENABLE);
if (port->slot_power_limit_value) {
sspl |= port->slot_power_limit_value << PCIE_SSPL_VALUE_SHIFT;
sspl |= port->slot_power_limit_scale << PCIE_SSPL_SCALE_SHIFT;
sspl |= PCIE_SSPL_ENABLE;
}
mvebu_writel(port, sspl, PCIE_SSPL_OFF);

/* Mask all interrupt sources. */
mvebu_writel(port, ~PCIE_INT_ALL_MASK, PCIE_INT_UNMASK_OFF);

Expand Down Expand Up @@ -628,9 +651,24 @@ mvebu_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
(PCI_EXP_LNKSTA_DLLLA << 16) : 0);
break;

case PCI_EXP_SLTCTL:
*value = PCI_EXP_SLTSTA_PDS << 16;
case PCI_EXP_SLTCTL: {
u16 slotctl = le16_to_cpu(bridge->pcie_conf.slotctl);
u16 slotsta = le16_to_cpu(bridge->pcie_conf.slotsta);
u32 val = 0;
/*
* When slot power limit was not specified in DT then
* ASPL_DISABLE bit is stored only in emulated config space.
* Otherwise reflect status of PCIE_SSPL_ENABLE bit in HW.
*/
if (!port->slot_power_limit_value)
val |= slotctl & PCI_EXP_SLTCTL_ASPL_DISABLE;
else if (!(mvebu_readl(port, PCIE_SSPL_OFF) & PCIE_SSPL_ENABLE))
val |= PCI_EXP_SLTCTL_ASPL_DISABLE;
/* This callback is 32-bit and in high bits is slot status. */
val |= slotsta << 16;
*value = val;
break;
}

case PCI_EXP_RTSTA:
*value = mvebu_readl(port, PCIE_RC_RTSTA);
Expand Down Expand Up @@ -774,6 +812,22 @@ mvebu_pci_bridge_emul_pcie_conf_write(struct pci_bridge_emul *bridge,
mvebu_writel(port, new, PCIE_CAP_PCIEXP + PCI_EXP_LNKCTL);
break;

case PCI_EXP_SLTCTL:
/*
* Allow to change PCIE_SSPL_ENABLE bit only when slot power
* limit was specified in DT and configured into HW.
*/
if ((mask & PCI_EXP_SLTCTL_ASPL_DISABLE) &&
port->slot_power_limit_value) {
u32 sspl = mvebu_readl(port, PCIE_SSPL_OFF);
if (new & PCI_EXP_SLTCTL_ASPL_DISABLE)
sspl &= ~PCIE_SSPL_ENABLE;
else
sspl |= PCIE_SSPL_ENABLE;
mvebu_writel(port, sspl, PCIE_SSPL_OFF);
}
break;

case PCI_EXP_RTSTA:
/*
* PME Status bit in Root Status Register (PCIE_RC_RTSTA)
Expand Down Expand Up @@ -868,8 +922,26 @@ static int mvebu_pci_bridge_emul_init(struct mvebu_pcie_port *port)
/*
* Older mvebu hardware provides PCIe Capability structure only in
* version 1. New hardware provides it in version 2.
* Enable slot support which is emulated.
*/
bridge->pcie_conf.cap = cpu_to_le16(pcie_cap_ver);
bridge->pcie_conf.cap = cpu_to_le16(pcie_cap_ver | PCI_EXP_FLAGS_SLOT);

/*
* Set Presence Detect State bit permanently as there is no support for
* unplugging PCIe card from the slot. Assume that PCIe card is always
* connected in slot.
*
* Set physical slot number to port+1 as mvebu ports are indexed from
* zero and zero value is reserved for ports within the same silicon
* as Root Port which is not mvebu case.
*
* Also set correct slot power limit.
*/
bridge->pcie_conf.slotcap = cpu_to_le32(
FIELD_PREP(PCI_EXP_SLTCAP_SPLV, port->slot_power_limit_value) |
FIELD_PREP(PCI_EXP_SLTCAP_SPLS, port->slot_power_limit_scale) |
FIELD_PREP(PCI_EXP_SLTCAP_PSN, port->port+1));
bridge->pcie_conf.slotsta = cpu_to_le16(PCI_EXP_SLTSTA_PDS);

bridge->subsystem_vendor_id = ssdev_id & 0xffff;
bridge->subsystem_id = ssdev_id >> 16;
Expand Down Expand Up @@ -1191,6 +1263,7 @@ static int mvebu_pcie_parse_port(struct mvebu_pcie *pcie,
{
struct device *dev = &pcie->pdev->dev;
enum of_gpio_flags flags;
u32 slot_power_limit;
int reset_gpio, ret;
u32 num_lanes;

Expand Down Expand Up @@ -1291,6 +1364,15 @@ static int mvebu_pcie_parse_port(struct mvebu_pcie *pcie,
port->reset_gpio = gpio_to_desc(reset_gpio);
}

slot_power_limit = of_pci_get_slot_power_limit(child,
&port->slot_power_limit_value,
&port->slot_power_limit_scale);
if (slot_power_limit)
dev_info(dev, "%s: Slot power limit %u.%uW\n",
port->name,
slot_power_limit / 1000,
(slot_power_limit / 100) % 10);

port->clk = of_clk_get_by_name(child, NULL);
if (IS_ERR(port->clk)) {
dev_err(dev, "%s: cannot get clock\n", port->name);
Expand Down Expand Up @@ -1588,7 +1670,7 @@ static int mvebu_pcie_remove(struct platform_device *pdev)
{
struct mvebu_pcie *pcie = platform_get_drvdata(pdev);
struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
u32 cmd;
u32 cmd, sspl;
int i;

/* Remove PCI bus with all devices. */
Expand Down Expand Up @@ -1625,6 +1707,11 @@ static int mvebu_pcie_remove(struct platform_device *pdev)
/* Free config space for emulated root bridge. */
pci_bridge_emul_cleanup(&port->bridge);

/* Disable sending Set_Slot_Power_Limit PCIe Message. */
sspl = mvebu_readl(port, PCIE_SSPL_OFF);
sspl &= ~(PCIE_SSPL_VALUE_MASK | PCIE_SSPL_SCALE_MASK | PCIE_SSPL_ENABLE);
mvebu_writel(port, sspl, PCIE_SSPL_OFF);

/* Disable and clear BARs and windows. */
mvebu_pcie_disable_wins(port);

Expand Down

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