[PATCH 01/13] PCI: tegra: Convert to MSI domains

From: Marc Zyngier
Date: Thu Feb 25 2021 - 10:11:55 EST

In anticipation of the removal of the msi_controller structure, convert
the Tegra host controller driver to MSI domains.

We end-up with the usual two domain structure, the top one being a
generic PCI/MSI domain, the bottom one being Tegra-specific and handling
the actual HW interrupt allocation.

While at it, convert the normal interrupt handler to a chained handler,
handle the controller's MSI IRQ edge triggered, support multiple MSIs
per device and use the AFI_MSI_EN_VEC* registers to provide MSI masking.

[treding@xxxxxxxxxx: fix, clean up and address TODOs from Marc's draft]
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
drivers/pci/controller/Kconfig | 1 -
drivers/pci/controller/pci-tegra.c | 343 ++++++++++++++++-------------
2 files changed, 185 insertions(+), 159 deletions(-)

diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
index 64e2f5e379aa..e7007e4028fc 100644
--- a/drivers/pci/controller/Kconfig
+++ b/drivers/pci/controller/Kconfig
@@ -41,7 +41,6 @@ config PCI_TEGRA
bool "NVIDIA Tegra PCIe controller"
depends on ARCH_TEGRA || COMPILE_TEST
depends on PCI_MSI_IRQ_DOMAIN
- select PCI_MSI_ARCH_FALLBACKS
help
Say Y here if you want support for the PCIe host controller found
on NVIDIA Tegra SoCs.
diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c
index 8fcabed7c6a6..eaba7b2fab4a 100644
--- a/drivers/pci/controller/pci-tegra.c
+++ b/drivers/pci/controller/pci-tegra.c
@@ -21,6 +21,7 @@
#include <linux/interrupt.h>
#include <linux/iopoll.h>
#include <linux/irq.h>
+#include <linux/irqchip/chained_irq.h>
#include <linux/irqdomain.h>
#include <linux/kernel.h>
#include <linux/init.h>
@@ -78,23 +79,8 @@
#define AFI_MSI_FPCI_BAR_ST 0x64
#define AFI_MSI_AXI_BAR_ST 0x68

-#define AFI_MSI_VEC0 0x6c
-#define AFI_MSI_VEC1 0x70
-#define AFI_MSI_VEC2 0x74
-#define AFI_MSI_VEC3 0x78
-#define AFI_MSI_VEC4 0x7c
-#define AFI_MSI_VEC5 0x80
-#define AFI_MSI_VEC6 0x84
-#define AFI_MSI_VEC7 0x88
-
-#define AFI_MSI_EN_VEC0 0x8c
-#define AFI_MSI_EN_VEC1 0x90
-#define AFI_MSI_EN_VEC2 0x94
-#define AFI_MSI_EN_VEC3 0x98
-#define AFI_MSI_EN_VEC4 0x9c
-#define AFI_MSI_EN_VEC5 0xa0
-#define AFI_MSI_EN_VEC6 0xa4
-#define AFI_MSI_EN_VEC7 0xa8
+#define AFI_MSI_VEC(x) (0x6c + ((x) * 4))
+#define AFI_MSI_EN_VEC(x) (0x8c + ((x) * 4))

#define AFI_CONFIGURATION 0xac
#define AFI_CONFIGURATION_EN_FPCI (1 << 0)
@@ -280,10 +266,10 @@
#define LINK_RETRAIN_TIMEOUT 100000 /* in usec */

struct tegra_msi {
- struct msi_controller chip;
DECLARE_BITMAP(used, INT_PCI_MSI_NR);
struct irq_domain *domain;
- struct mutex lock;
+ struct mutex map_lock;
+ spinlock_t mask_lock;
void *virt;
dma_addr_t phys;
int irq;
@@ -333,11 +319,6 @@ struct tegra_pcie_soc {
} ectl;
};

-static inline struct tegra_msi *to_tegra_msi(struct msi_controller *chip)
-{
- return container_of(chip, struct tegra_msi, chip);
-}
-
struct tegra_pcie {
struct device *dev;

@@ -372,6 +353,11 @@ struct tegra_pcie {
struct dentry *debugfs;
};

+static inline struct tegra_pcie *msi_to_pcie(struct tegra_msi *msi)
+{
+ return container_of(msi, struct tegra_pcie, msi);
+}
+
struct tegra_pcie_port {
struct tegra_pcie *pcie;
struct device_node *np;
@@ -1432,7 +1418,6 @@ static void tegra_pcie_phys_put(struct tegra_pcie *pcie)
}
}

-
static int tegra_pcie_get_resources(struct tegra_pcie *pcie)
{
struct device *dev = pcie->dev;
@@ -1509,6 +1494,7 @@ static int tegra_pcie_get_resources(struct tegra_pcie *pcie)
phys_put:
if (soc->program_uphy)
tegra_pcie_phys_put(pcie);
+
return err;
}

@@ -1551,161 +1537,227 @@ static void tegra_pcie_pme_turnoff(struct tegra_pcie_port *port)
afi_writel(pcie, val, AFI_PCIE_PME);
}

-static int tegra_msi_alloc(struct tegra_msi *chip)
-{
- int msi;
-
- mutex_lock(&chip->lock);
-
- msi = find_first_zero_bit(chip->used, INT_PCI_MSI_NR);
- if (msi < INT_PCI_MSI_NR)
- set_bit(msi, chip->used);
- else
- msi = -ENOSPC;
-
- mutex_unlock(&chip->lock);
-
- return msi;
-}
-
-static void tegra_msi_free(struct tegra_msi *chip, unsigned long irq)
+static void tegra_pcie_msi_irq(struct irq_desc *desc)
{
- struct device *dev = chip->chip.dev;
-
- mutex_lock(&chip->lock);
-
- if (!test_bit(irq, chip->used))
- dev_err(dev, "trying to free unused MSI#%lu\n", irq);
- else
- clear_bit(irq, chip->used);
-
- mutex_unlock(&chip->lock);
-}
-
-static irqreturn_t tegra_pcie_msi_irq(int irq, void *data)
-{
- struct tegra_pcie *pcie = data;
- struct device *dev = pcie->dev;
+ struct tegra_pcie *pcie = irq_desc_get_handler_data(desc);
+ struct irq_chip *chip = irq_desc_get_chip(desc);
struct tegra_msi *msi = &pcie->msi;
- unsigned int i, processed = 0;
+ struct device *dev = pcie->dev;
+ unsigned int i;
+
+ chained_irq_enter(chip, desc);

for (i = 0; i < 8; i++) {
- unsigned long reg = afi_readl(pcie, AFI_MSI_VEC0 + i * 4);
+ unsigned long reg = afi_readl(pcie, AFI_MSI_VEC(i));

while (reg) {
unsigned int offset = find_first_bit(&reg, 32);
unsigned int index = i * 32 + offset;
unsigned int irq;

- /* clear the interrupt */
- afi_writel(pcie, 1 << offset, AFI_MSI_VEC0 + i * 4);
-
- irq = irq_find_mapping(msi->domain, index);
+ irq = irq_find_mapping(msi->domain->parent, index);
if (irq) {
- if (test_bit(index, msi->used))
- generic_handle_irq(irq);
- else
- dev_info(dev, "unhandled MSI\n");
+ generic_handle_irq(irq);
} else {
/*
* that's weird who triggered this?
* just clear it
*/
dev_info(dev, "unexpected MSI\n");
+ afi_writel(pcie, BIT(index % 32), AFI_MSI_VEC(index));
}

/* see if there's any more pending in this vector */
- reg = afi_readl(pcie, AFI_MSI_VEC0 + i * 4);
-
- processed++;
+ reg = afi_readl(pcie, AFI_MSI_VEC(i));
}
}

- return processed > 0 ? IRQ_HANDLED : IRQ_NONE;
+ chained_irq_exit(chip, desc);
}

-static int tegra_msi_setup_irq(struct msi_controller *chip,
- struct pci_dev *pdev, struct msi_desc *desc)
+static void tegra_msi_top_irq_ack(struct irq_data *d)
{
- struct tegra_msi *msi = to_tegra_msi(chip);
- struct msi_msg msg;
- unsigned int irq;
- int hwirq;
+ irq_chip_ack_parent(d);
+}

- hwirq = tegra_msi_alloc(msi);
- if (hwirq < 0)
- return hwirq;
+static void tegra_msi_top_irq_mask(struct irq_data *d)
+{
+ pci_msi_mask_irq(d);
+ irq_chip_mask_parent(d);
+}

- irq = irq_create_mapping(msi->domain, hwirq);
- if (!irq) {
- tegra_msi_free(msi, hwirq);
- return -EINVAL;
- }
+static void tegra_msi_top_irq_unmask(struct irq_data *d)
+{
+ pci_msi_unmask_irq(d);
+ irq_chip_unmask_parent(d);
+}
+
+static struct irq_chip tegra_msi_top_chip = {
+ .name = "tegra PCIe MSI",
+ .irq_ack = tegra_msi_top_irq_ack,
+ .irq_mask = tegra_msi_top_irq_mask,
+ .irq_unmask = tegra_msi_top_irq_unmask,
+};

- irq_set_msi_desc(irq, desc);
+static void tegra_msi_irq_ack(struct irq_data *d)
+{
+ struct tegra_msi *msi = irq_data_get_irq_chip_data(d);
+ struct tegra_pcie *pcie = msi_to_pcie(msi);
+ unsigned int index = d->hwirq / 32;

- msg.address_lo = lower_32_bits(msi->phys);
- msg.address_hi = upper_32_bits(msi->phys);
- msg.data = hwirq;
+ /* clear the interrupt */
+ afi_writel(pcie, BIT(d->hwirq % 32), AFI_MSI_VEC(index));
+}

- pci_write_msi_msg(irq, &msg);
+static void tegra_msi_irq_mask(struct irq_data *d)
+{
+ struct tegra_msi *msi = irq_data_get_irq_chip_data(d);
+ struct tegra_pcie *pcie = msi_to_pcie(msi);
+ unsigned int index = d->hwirq / 32;
+ unsigned long flags;
+ u32 value;

- return 0;
+ spin_lock_irqsave(&msi->mask_lock, flags);
+ value = afi_readl(pcie, AFI_MSI_EN_VEC(index));
+ value &= ~BIT(d->hwirq % 32);
+ afi_writel(pcie, value, AFI_MSI_EN_VEC(index));
+ spin_unlock_irqrestore(&msi->mask_lock, flags);
+}
+
+static void tegra_msi_irq_unmask(struct irq_data *d)
+{
+ struct tegra_msi *msi = irq_data_get_irq_chip_data(d);
+ struct tegra_pcie *pcie = msi_to_pcie(msi);
+ unsigned int index = d->hwirq / 32;
+ unsigned long flags;
+ u32 value;
+
+ spin_lock_irqsave(&msi->mask_lock, flags);
+ value = afi_readl(pcie, AFI_MSI_EN_VEC(index));
+ value |= BIT(d->hwirq % 32);
+ afi_writel(pcie, value, AFI_MSI_EN_VEC(index));
+ spin_unlock_irqrestore(&msi->mask_lock, flags);
+}
+
+static int tegra_msi_set_affinity(struct irq_data *d, const struct cpumask *mask, bool force)
+{
+ return -EINVAL;
}

-static void tegra_msi_teardown_irq(struct msi_controller *chip,
- unsigned int irq)
+static void tegra_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
- struct tegra_msi *msi = to_tegra_msi(chip);
- struct irq_data *d = irq_get_irq_data(irq);
- irq_hw_number_t hwirq = irqd_to_hwirq(d);
+ struct tegra_msi *msi = irq_data_get_irq_chip_data(data);

- irq_dispose_mapping(irq);
- tegra_msi_free(msi, hwirq);
+ msg->address_lo = lower_32_bits(msi->phys);
+ msg->address_hi = upper_32_bits(msi->phys);
+ msg->data = data->hwirq;
}

-static struct irq_chip tegra_msi_irq_chip = {
- .name = "Tegra PCIe MSI",
- .irq_enable = pci_msi_unmask_irq,
- .irq_disable = pci_msi_mask_irq,
- .irq_mask = pci_msi_mask_irq,
- .irq_unmask = pci_msi_unmask_irq,
+static struct irq_chip tegra_msi_bottom_chip = {
+ .name = "Tegra MSI",
+ .irq_ack = tegra_msi_irq_ack,
+ .irq_mask = tegra_msi_irq_mask,
+ .irq_unmask = tegra_msi_irq_unmask,
+ .irq_set_affinity = tegra_msi_set_affinity,
+ .irq_compose_msi_msg = tegra_compose_msi_msg,
};

-static int tegra_msi_map(struct irq_domain *domain, unsigned int irq,
- irq_hw_number_t hwirq)
+static int tegra_msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
+ unsigned int nr_irqs, void *args)
{
- irq_set_chip_and_handler(irq, &tegra_msi_irq_chip, handle_simple_irq);
- irq_set_chip_data(irq, domain->host_data);
+ struct tegra_msi *msi = domain->host_data;
+ unsigned int i;
+ int hwirq;
+
+ mutex_lock(&msi->map_lock);
+
+ hwirq = bitmap_find_free_region(msi->used, INT_PCI_MSI_NR, order_base_2(nr_irqs));
+
+ mutex_unlock(&msi->map_lock);
+
+ if (hwirq < 0)
+ return -ENOSPC;
+
+ for (i = 0; i < nr_irqs; i++)
+ irq_domain_set_info(domain, virq + i, hwirq + i,
+ &tegra_msi_bottom_chip, domain->host_data,
+ handle_edge_irq, NULL, NULL);

tegra_cpuidle_pcie_irqs_in_use();

return 0;
}

-static const struct irq_domain_ops msi_domain_ops = {
- .map = tegra_msi_map,
+static void tegra_msi_domain_free(struct irq_domain *domain, unsigned int virq,
+ unsigned int nr_irqs)
+{
+ struct irq_data *d = irq_domain_get_irq_data(domain, virq);
+ struct tegra_msi *msi = domain->host_data;
+
+ mutex_lock(&msi->map_lock);
+
+ bitmap_release_region(msi->used, d->hwirq, order_base_2(nr_irqs));
+
+ mutex_unlock(&msi->map_lock);
+}
+
+static const struct irq_domain_ops tegra_msi_domain_ops = {
+ .alloc = tegra_msi_domain_alloc,
+ .free = tegra_msi_domain_free,
+};
+
+static struct msi_domain_info tegra_msi_info = {
+ .flags = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
+ MSI_FLAG_PCI_MSIX),
+ .chip = &tegra_msi_top_chip,
};

+static int tegra_allocate_domains(struct tegra_msi *msi)
+{
+ struct tegra_pcie *pcie = msi_to_pcie(msi);
+ struct fwnode_handle *fwnode = dev_fwnode(pcie->dev);
+ struct irq_domain *parent;
+
+ parent = irq_domain_create_linear(fwnode, INT_PCI_MSI_NR,
+ &tegra_msi_domain_ops, msi);
+ if (!parent) {
+ dev_err(pcie->dev, "failed to create IRQ domain\n");
+ return -ENOMEM;
+ }
+ irq_domain_update_bus_token(parent, DOMAIN_BUS_NEXUS);
+
+ msi->domain = pci_msi_create_irq_domain(fwnode, &tegra_msi_info, parent);
+ if (!msi->domain) {
+ dev_err(pcie->dev, "failed to create MSI domain\n");
+ irq_domain_remove(parent);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static void tegra_free_domains(struct tegra_msi *msi)
+{
+ struct irq_domain *parent = msi->domain->parent;
+
+ irq_domain_remove(msi->domain);
+ irq_domain_remove(parent);
+}
+
static int tegra_pcie_msi_setup(struct tegra_pcie *pcie)
{
- struct pci_host_bridge *host = pci_host_bridge_from_priv(pcie);
struct platform_device *pdev = to_platform_device(pcie->dev);
struct tegra_msi *msi = &pcie->msi;
struct device *dev = pcie->dev;
int err;

- mutex_init(&msi->lock);
-
- msi->chip.dev = dev;
- msi->chip.setup_irq = tegra_msi_setup_irq;
- msi->chip.teardown_irq = tegra_msi_teardown_irq;
+ mutex_init(&msi->map_lock);
+ spin_lock_init(&msi->mask_lock);

- msi->domain = irq_domain_add_linear(dev->of_node, INT_PCI_MSI_NR,
- &msi_domain_ops, &msi->chip);
- if (!msi->domain) {
- dev_err(dev, "failed to create IRQ domain\n");
- return -ENOMEM;
+ if (IS_ENABLED(CONFIG_PCI_MSI)) {
+ err = tegra_allocate_domains(msi);
+ if (err)
+ return err;
}

err = platform_get_irq_byname(pdev, "msi");
@@ -1714,12 +1766,7 @@ static int tegra_pcie_msi_setup(struct tegra_pcie *pcie)

msi->irq = err;

- err = request_irq(msi->irq, tegra_pcie_msi_irq, IRQF_NO_THREAD,
- tegra_msi_irq_chip.name, pcie);
- if (err < 0) {
- dev_err(dev, "failed to request IRQ: %d\n", err);
- goto free_irq_domain;
- }
+ irq_set_chained_handler_and_data(msi->irq, tegra_pcie_msi_irq, pcie);

/* Though the PCIe controller can address >32-bit address space, to
* facilitate endpoints that support only 32-bit MSI target address,
@@ -1740,14 +1787,14 @@ static int tegra_pcie_msi_setup(struct tegra_pcie *pcie)
goto free_irq;
}

- host->msi = &msi->chip;
-
return 0;

free_irq:
- free_irq(msi->irq, pcie);
+ irq_set_chained_handler_and_data(msi->irq, NULL, NULL);
free_irq_domain:
- irq_domain_remove(msi->domain);
+ if (IS_ENABLED(CONFIG_PCI_MSI))
+ tegra_free_domains(msi);
+
return err;
}

@@ -1762,16 +1809,6 @@ static void tegra_pcie_enable_msi(struct tegra_pcie *pcie)
/* this register is in 4K increments */
afi_writel(pcie, 1, AFI_MSI_BAR_SZ);

- /* enable all MSI vectors */
- afi_writel(pcie, 0xffffffff, AFI_MSI_EN_VEC0);
- afi_writel(pcie, 0xffffffff, AFI_MSI_EN_VEC1);
- afi_writel(pcie, 0xffffffff, AFI_MSI_EN_VEC2);
- afi_writel(pcie, 0xffffffff, AFI_MSI_EN_VEC3);
- afi_writel(pcie, 0xffffffff, AFI_MSI_EN_VEC4);
- afi_writel(pcie, 0xffffffff, AFI_MSI_EN_VEC5);
- afi_writel(pcie, 0xffffffff, AFI_MSI_EN_VEC6);
- afi_writel(pcie, 0xffffffff, AFI_MSI_EN_VEC7);
-
/* and unmask the MSI interrupt */
reg = afi_readl(pcie, AFI_INTR_MASK);
reg |= AFI_INTR_MASK_MSI_MASK;
@@ -1786,16 +1823,16 @@ static void tegra_pcie_msi_teardown(struct tegra_pcie *pcie)
dma_free_attrs(pcie->dev, PAGE_SIZE, msi->virt, msi->phys,
DMA_ATTR_NO_KERNEL_MAPPING);

- if (msi->irq > 0)
- free_irq(msi->irq, pcie);
-
for (i = 0; i < INT_PCI_MSI_NR; i++) {
irq = irq_find_mapping(msi->domain, i);
if (irq > 0)
- irq_dispose_mapping(irq);
+ irq_domain_free_irqs(irq, 1);
}

- irq_domain_remove(msi->domain);
+ irq_set_chained_handler_and_data(msi->irq, NULL, NULL);
+
+ if (IS_ENABLED(CONFIG_PCI_MSI))
+ tegra_free_domains(msi);
}

static int tegra_pcie_disable_msi(struct tegra_pcie *pcie)
@@ -1807,16 +1844,6 @@ static int tegra_pcie_disable_msi(struct tegra_pcie *pcie)
value &= ~AFI_INTR_MASK_MSI_MASK;
afi_writel(pcie, value, AFI_INTR_MASK);

- /* disable all MSI vectors */
- afi_writel(pcie, 0, AFI_MSI_EN_VEC0);
- afi_writel(pcie, 0, AFI_MSI_EN_VEC1);
- afi_writel(pcie, 0, AFI_MSI_EN_VEC2);
- afi_writel(pcie, 0, AFI_MSI_EN_VEC3);
- afi_writel(pcie, 0, AFI_MSI_EN_VEC4);
- afi_writel(pcie, 0, AFI_MSI_EN_VEC5);
- afi_writel(pcie, 0, AFI_MSI_EN_VEC6);
- afi_writel(pcie, 0, AFI_MSI_EN_VEC7);
-
return 0;
}

--
2.29.2