Re: [PATCH v2 4/5] PCI: iproc: Add iProc PCIe MSI support
From: Ray Jui
Date: Wed Nov 25 2015 - 20:52:49 EST
Hi Marc,
On 11/25/2015 9:36 AM, Marc Zyngier wrote:
On Tue, 24 Nov 2015 15:04:53 -0800
Ray Jui <rjui@xxxxxxxxxxxx> wrote:
This patch adds PCIe MSI support for both PAXB and PAXC interfaces on
all iProc based platforms. The patch follows the latest trend in the
kernel to use MSI domain based implementation
That's a pretty useless comment. The general trend in the kernel is to
use the most appropriate infrastructure.
This iProc event queue based MSI support should not be used with newer
platforms with integrated MSI support in the GIC (e.g., giv2m or
gicv3-its)
I'd be more interested in some documentation explaining how the HW
works, how the various data structures are updated, and when.
Okay will try my best to describe my understanding of iProc MSI in the
commit message of my next iteration of patches.
Signed-off-by: Ray Jui <rjui@xxxxxxxxxxxx>
Reviewed-by: Anup Patel <anup.patel@xxxxxxxxxxxx>
Reviewed-by: Vikram Prakash <vikramp@xxxxxxxxxxxx>
Reviewed-by: Scott Branden <sbranden@xxxxxxxxxxxx>
---
drivers/pci/host/Kconfig | 9 +
drivers/pci/host/Makefile | 1 +
drivers/pci/host/pcie-iproc-msi.c | 662 ++++++++++++++++++++++++++++++++++++++
drivers/pci/host/pcie-iproc.c | 26 ++
drivers/pci/host/pcie-iproc.h | 21 +-
5 files changed, 717 insertions(+), 2 deletions(-)
create mode 100644 drivers/pci/host/pcie-iproc-msi.c
diff --git a/drivers/pci/host/Kconfig b/drivers/pci/host/Kconfig
index f131ba9..972e906 100644
--- a/drivers/pci/host/Kconfig
+++ b/drivers/pci/host/Kconfig
@@ -126,6 +126,15 @@ config PCIE_IPROC
iProc family of SoCs. An appropriate bus interface driver also needs
to be enabled
+config PCIE_IPROC_MSI
+ bool "Broadcom iProc PCIe MSI support"
+ depends on ARCH_BCM_IPROC && PCI_MSI
+ select PCI_MSI_IRQ_DOMAIN
+ default ARCH_BCM_IPROC
+ help
+ Say Y here if you want to enable MSI support for Broadcom's iProc
+ PCIe controller
+
config PCIE_IPROC_PLATFORM
tristate "Broadcom iProc PCIe platform bus driver"
depends on ARCH_BCM_IPROC || (ARM && COMPILE_TEST)
diff --git a/drivers/pci/host/Makefile b/drivers/pci/host/Makefile
index 9d4d3c6..0e4e95e 100644
--- a/drivers/pci/host/Makefile
+++ b/drivers/pci/host/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_PCI_XGENE_MSI) += pci-xgene-msi.o
obj-$(CONFIG_PCI_LAYERSCAPE) += pci-layerscape.o
obj-$(CONFIG_PCI_VERSATILE) += pci-versatile.o
obj-$(CONFIG_PCIE_IPROC) += pcie-iproc.o
+obj-$(CONFIG_PCIE_IPROC_MSI) += pcie-iproc-msi.o
obj-$(CONFIG_PCIE_IPROC_PLATFORM) += pcie-iproc-platform.o
obj-$(CONFIG_PCIE_IPROC_BCMA) += pcie-iproc-bcma.o
obj-$(CONFIG_PCIE_ALTERA) += pcie-altera.o
diff --git a/drivers/pci/host/pcie-iproc-msi.c b/drivers/pci/host/pcie-iproc-msi.c
new file mode 100644
index 0000000..afc54c2
--- /dev/null
+++ b/drivers/pci/host/pcie-iproc-msi.c
@@ -0,0 +1,662 @@
+/*
+ * Copyright (C) 2015 Broadcom Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/msi.h>
+#include <linux/of_irq.h>
+#include <linux/of_pci.h>
+#include <linux/pci.h>
+
+#include "pcie-iproc.h"
+
+#define IPROC_MSI_INTR_EN_SHIFT 11
+#define IPROC_MSI_INTR_EN BIT(IPROC_MSI_INTR_EN_SHIFT)
+#define IPROC_MSI_INT_N_EVENT_SHIFT 1
+#define IPROC_MSI_INT_N_EVENT BIT(IPROC_MSI_INT_N_EVENT_SHIFT)
+#define IPROC_MSI_EQ_EN_SHIFT 0
+#define IPROC_MSI_EQ_EN BIT(IPROC_MSI_EQ_EN_SHIFT)
+
+#define IPROC_MSI_EQ_MASK 0x3f
+
+/* max number of GIC interrupts */
+#define NR_HW_IRQS 6
+
+/* number of entries in each event queue */
+#define EQ_LEN 64
+
+/* size of each event queue memory region */
+#define EQ_MEM_REGION_SIZE SZ_4K
+
+/* size of each MSI message memory region */
+#define MSI_MEM_REGION_SIZE SZ_4K
+
+enum iproc_msi_reg {
+ IPROC_MSI_EQ_PAGE = 0,
+ IPROC_MSI_EQ_PAGE_UPPER,
+ IPROC_MSI_PAGE,
+ IPROC_MSI_PAGE_UPPER,
+ IPROC_MSI_CTRL,
+ IPROC_MSI_EQ_HEAD,
+ IPROC_MSI_EQ_TAIL,
+ IPROC_MSI_INTS_EN,
+ IPROC_MSI_REG_SIZE,
+};
+
+struct iproc_msi;
+
+/**
+ * iProc MSI group
+ *
+ * One MSI group is allocated per GIC interrupt, serviced by one iProc MSI
+ * event queue
+ *
+ * @msi: pointer to iProc MSI data
+ * @gic_irq: GIC interrupt
+ * @eq: Event queue number
+ */
+struct iproc_msi_grp {
+ struct iproc_msi *msi;
+ int gic_irq;
+ unsigned int eq;
+};
+
+/**
+ * iProc event queue based MSI
+ *
+ * Only meant to be used on platforms without MSI support integrated into the
+ * GIC
+ *
+ * @pcie: pointer to iProc PCIe data
+ * @reg_offsets: MSI register offsets
+ * @grps: MSI groups
+ * @nr_irqs: number of total interrupts connected to GIC
+ * @nr_cpus: number of toal CPUs
+ * @has_inten_reg: indicates the MSI interrupt enable register needs to be
+ * set explicitly (required for some legacy platforms)
+ * @bitmap: MSI vector bitmap
+ * @bitmap_lock: lock to protect access to the MSI bitmap
+ * @nr_msi_vecs: total number of MSI vectors
+ * @inner_domain: inner IRQ domain
+ * @msi_domain: MSI IRQ domain
+ * @nr_eq_region: required number of 4K aligned memory region for MSI event
+ * queues
+ * @nr_msi_region: required number of 4K aligned memory region for MSI posted
+ * writes
+ * @eq_cpu: pointer to allocated memory region for MSI event queues
+ * @eq_dma: DMA address of MSI event queues
+ * @msi_cpu: pointer to allocated memory region for MSI posted writes
+ * @msi_dma: DMA address of MSI posted writes
+ */
+struct iproc_msi {
+ struct iproc_pcie *pcie;
+ const u16 (*reg_offsets)[IPROC_MSI_REG_SIZE];
+ struct iproc_msi_grp *grps;
+ int nr_irqs;
+ int nr_cpus;
+ bool has_inten_reg;
+ unsigned long *bitmap;
+ struct mutex bitmap_lock;
+ unsigned int nr_msi_vecs;
+ struct irq_domain *inner_domain;
+ struct irq_domain *msi_domain;
+ unsigned int nr_eq_region;
+ unsigned int nr_msi_region;
+ void *eq_cpu;
+ dma_addr_t eq_dma;
+ void *msi_cpu;
+ dma_addr_t msi_dma;
+};
+
+static const u16 iproc_msi_reg_paxb[NR_HW_IRQS][IPROC_MSI_REG_SIZE] = {
+ { 0x200, 0x2c0, 0x204, 0x2c4, 0x210, 0x250, 0x254, 0x208 },
+ { 0x200, 0x2c0, 0x204, 0x2c4, 0x214, 0x258, 0x25c, 0x208 },
+ { 0x200, 0x2c0, 0x204, 0x2c4, 0x218, 0x260, 0x264, 0x208 },
+ { 0x200, 0x2c0, 0x204, 0x2c4, 0x21c, 0x268, 0x26c, 0x208 },
+ { 0x200, 0x2c0, 0x204, 0x2c4, 0x220, 0x270, 0x274, 0x208 },
+ { 0x200, 0x2c0, 0x204, 0x2c4, 0x224, 0x278, 0x27c, 0x208 },
+};
+
+static const u16 iproc_msi_reg_paxc[NR_HW_IRQS][IPROC_MSI_REG_SIZE] = {
+ { 0xc00, 0xc04, 0xc08, 0xc0c, 0xc40, 0xc50, 0xc60 },
+ { 0xc10, 0xc14, 0xc18, 0xc1c, 0xc44, 0xc54, 0xc64 },
+ { 0xc20, 0xc24, 0xc28, 0xc2c, 0xc48, 0xc58, 0xc68 },
+ { 0xc30, 0xc34, 0xc38, 0xc3c, 0xc4c, 0xc5c, 0xc6c },
+};
+
+static inline u32 iproc_msi_read_reg(struct iproc_msi *msi,
+ enum iproc_msi_reg reg,
+ unsigned int eq)
+{
+ struct iproc_pcie *pcie = msi->pcie;
+
+ return readl_relaxed(pcie->base + msi->reg_offsets[eq][reg]);
+}
+
+static inline void iproc_msi_write_reg(struct iproc_msi *msi,
+ enum iproc_msi_reg reg,
+ int eq, u32 val)
+{
+ struct iproc_pcie *pcie = msi->pcie;
+
+ writel_relaxed(val, pcie->base + msi->reg_offsets[eq][reg]);
+}
+
+static inline bool iproc_msi_has_mult_regions(struct iproc_msi *msi)
+{
+ return ((msi->nr_msi_region > 1) ? true : false);
return msi->nr_msi_region > 1;
Will change this function to return the multiplier according to your
comment below.
+}
+
+static inline bool iproc_eq_has_mult_regions(struct iproc_msi *msi)
+{
+ return ((msi->nr_eq_region > 1) ? true : false);
return msi->nr_eq_region > 1;
Will change this function to return the offsets directly.
+}
+
+static struct irq_chip iproc_msi_irq_chip = {
+ .name = "iProc-MSI",
+};
+
+static struct msi_domain_info iproc_msi_domain_info = {
+ .flags = MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
+ MSI_FLAG_PCI_MSIX,
+ .chip = &iproc_msi_irq_chip,
+};
+
+/*
+ * In iProc PCIe core, each MSI group is serviced by a GIC interrupt and a
+ * dedicated event queue. Each MSI group can support up to 64 MSI vectors
+ *
+ * The number of MSI groups varies between different iProc SoCs. The total
+ * number of CPU cores also varies. To support MSI IRQ affinity, we
+ * distribute GIC interrupts across all available CPUs. MSI vector is moved
+ * from one GIC interrupt to another to steer to the target CPU
+ *
+ * Assuming:
+ * - the number of MSI groups is M
+ * - the number of CPU cores is N
+ * - M is always a multiple of N
How do you enforce that last condition?
Okay I need to enforce this as soon as the number of GIC interrupts is
determined from DT in the init routine. I will add code to enforce this
condition.
+ *
+ * Total number of raw MSI vectors = M * 64
+ * Total number of supported MSI vectors = (M * 64) / N
+ */
+static inline int hwirq_to_cpu(struct iproc_msi *msi, unsigned long hwirq)
+{
+ return (hwirq % msi->nr_cpus);
+}
+
+static inline unsigned long hwirq_to_canonical_hwirq(struct iproc_msi *msi,
+ unsigned long hwirq)
+{
+ return (hwirq - hwirq_to_cpu(msi, hwirq));
+}
+
+static int iproc_msi_irq_set_affinity(struct irq_data *data,
+ const struct cpumask *mask, bool force)
+{
+ struct iproc_msi *msi = irq_data_get_irq_chip_data(data);
+ int target_cpu = cpumask_first(mask);
+ int curr_cpu;
+
+ curr_cpu = hwirq_to_cpu(msi, data->hwirq);
+ if (curr_cpu == target_cpu)
+ return IRQ_SET_MASK_OK_DONE;
+
+ /* steer MSI to the target CPU */
+ data->hwirq = hwirq_to_canonical_hwirq(msi, data->hwirq) + target_cpu;
+
+ return IRQ_SET_MASK_OK;
+}
+
+static inline u32 hwirq_to_group(struct iproc_msi *msi, unsigned long hwirq)
+{
+ return (hwirq % msi->nr_irqs);
+}
+
+static void iproc_msi_irq_compose_msi_msg(struct irq_data *data,
+ struct msi_msg *msg)
+{
+ struct iproc_msi *msi = irq_data_get_irq_chip_data(data);
+ dma_addr_t addr;
+ unsigned int mul;
+
+ if (iproc_msi_has_mult_regions(msi))
+ mul = MSI_MEM_REGION_SIZE;
+ else
+ mul = sizeof(u32);
Since this is the only use of that function, why don't you have it to
directly return the right multiplier?
True, that will make the above code simpler just one line. Will do!
+
+ addr = msi->msi_dma + hwirq_to_group(msi, data->hwirq) * mul;
+ msg->address_lo = lower_32_bits(addr);
+ msg->address_hi = upper_32_bits(addr);
+ msg->data = data->hwirq;
+}
+
+static struct irq_chip iproc_msi_bottom_irq_chip = {
+ .name = "MSI",
+ .irq_set_affinity = iproc_msi_irq_set_affinity,
+ .irq_compose_msi_msg = iproc_msi_irq_compose_msi_msg,
+};
+
+static int iproc_msi_irq_domain_alloc(struct irq_domain *domain,
+ unsigned int virq, unsigned int nr_irqs,
+ void *args)
+{
+ struct iproc_msi *msi = domain->host_data;
+ int hwirq;
+
+ mutex_lock(&msi->bitmap_lock);
+
+ /* allocate 'nr_cpus' number of MSI vectors each time */
+ hwirq = bitmap_find_next_zero_area(msi->bitmap, msi->nr_msi_vecs, 0,
+ msi->nr_cpus, 0);
+ if (hwirq < msi->nr_msi_vecs)
+ bitmap_set(msi->bitmap, hwirq, msi->nr_cpus);
+ else
+ return -ENOSPC;
Deadlock, here we come...
Damn it. My bad. Will fix.
+
+ mutex_unlock(&msi->bitmap_lock);
+
+ irq_domain_set_info(domain, virq, hwirq, &iproc_msi_bottom_irq_chip,
+ domain->host_data, handle_simple_irq, NULL, NULL);
+
+ return 0;
+}
+
+static void iproc_msi_irq_domain_free(struct irq_domain *domain,
+ unsigned int virq, unsigned int nr_irqs)
+{
+ struct irq_data *data = irq_domain_get_irq_data(domain, virq);
+ struct iproc_msi *msi = irq_data_get_irq_chip_data(data);
+ unsigned int hwirq;
+
+ mutex_lock(&msi->bitmap_lock);
+
+ hwirq = hwirq_to_canonical_hwirq(msi, data->hwirq);
+ bitmap_clear(msi->bitmap, hwirq, msi->nr_cpus);
+
+ mutex_unlock(&msi->bitmap_lock);
+
+ irq_domain_free_irqs_parent(domain, virq, nr_irqs);
+}
+
+static const struct irq_domain_ops msi_domain_ops = {
+ .alloc = iproc_msi_irq_domain_alloc,
+ .free = iproc_msi_irq_domain_free,
+};
+
+static inline u32 decode_msi_hwirq(struct iproc_msi *msi, u32 eq, u32 head)
+{
+ u32 *msg, hwirq;
+ unsigned int offs;
+
+ if (iproc_eq_has_mult_regions(msi))
+ offs = eq * EQ_MEM_REGION_SIZE;
+ else
+ offs = eq * EQ_LEN * sizeof(u32);
Same here.
Okay. Will change the code. Thanks.
+
+ offs += head * sizeof(u32);
+ msg = (u32 *)(msi->eq_cpu + offs);
If that's the only place where you dereference msi->eq_cpu, why doesn't
it have the right type?
Okay this really caught me, :) I actually changed msi->eq_cpu to type
'u32 *' and found things all of a sudden stopped working. Then I
realized it's a lot easier to let msi->eq_cpu stay as 'void *', so we
can keep the arithmetic to calcualte 'offs' as it is. If I change it to
'u32 *', then I would need to divide 'offs' by sizeof(u32) to get right
address of the pointer.
+ hwirq = *msg & IPROC_MSI_EQ_MASK;
+
+ /*
+ * Since we have multiple hwirq mapped to a single MSI vector,
+ * now we need to derive the hwirq at CPU0. It can then be used to
+ * mapped back to virq
+ */
+ return hwirq_to_canonical_hwirq(msi, hwirq);
+}
+
+static void iproc_msi_handler(struct irq_desc *desc)
+{
+ struct irq_chip *chip = irq_desc_get_chip(desc);
+ struct iproc_msi_grp *grp;
+ struct iproc_msi *msi;
+ struct iproc_pcie *pcie;
+ u32 eq, head, tail, nr_events;
+ unsigned long hwirq;
+ int virq;
+
+ chained_irq_enter(chip, desc);
+
+ grp = irq_desc_get_handler_data(desc);
+ msi = grp->msi;
+ pcie = msi->pcie;
+ eq = grp->eq;
+
+ /*
+ * iProc MSI event queue is tracked by head and tail pointers. Head
+ * pointer indicates the next entry to be processed by SW in the
+ * queue. Entries between head and tail pointers contain valid MSI
+ * data to be processed
+ */
+ head = iproc_msi_read_reg(msi, IPROC_MSI_EQ_HEAD,
+ eq) & IPROC_MSI_EQ_MASK;
+ do {
+ tail = iproc_msi_read_reg(msi, IPROC_MSI_EQ_TAIL,
+ eq) & IPROC_MSI_EQ_MASK;
+
+ /*
+ * Figure out total number of events (MSI data) to be
+ * processed
+ */
+ nr_events = (tail < head) ?
+ (EQ_LEN - (head - tail)) : (tail - head);
+ if (!nr_events)
+ break;
+
+ /* process all outstanding events */
+ while (nr_events--) {
+ hwirq = decode_msi_hwirq(msi, eq, head);
+ virq = irq_find_mapping(msi->inner_domain, hwirq);
+ generic_handle_irq(virq);
+
+ head++;
+ head %= EQ_LEN;
+ iproc_msi_write_reg(msi, IPROC_MSI_EQ_HEAD, eq, head);
+ }
Wouldn't it be better to process all nr_events and only update head
once?
You are right. That will help to get rid of the overhead of repeatedly
writing to the event queue head register. Will make the change.
+
+ /*
+ * Now go read the tail pointer again to see if there are new
+ * oustanding events that came in during the above window
+ */
+ } while (true);
+
+ chained_irq_exit(chip, desc);
+}
+
+static void iproc_msi_enable(struct iproc_msi *msi)
+{
+ int i, eq;
+ u32 val;
+
+ /* program memory region for each event queue */
+ for (i = 0; i < msi->nr_eq_region; i++) {
+ dma_addr_t addr = msi->eq_dma + (i * EQ_MEM_REGION_SIZE);
+
+ iproc_msi_write_reg(msi, IPROC_MSI_EQ_PAGE, i,
+ lower_32_bits(addr));
+ iproc_msi_write_reg(msi, IPROC_MSI_EQ_PAGE_UPPER, i,
+ upper_32_bits(addr));
+ }
+
+ /* program memory region for MSI posted writes */
+ for (i = 0; i < msi->nr_msi_region; i++) {
+ dma_addr_t addr = msi->msi_dma + (i * MSI_MEM_REGION_SIZE);
+
+ iproc_msi_write_reg(msi, IPROC_MSI_PAGE, i,
+ lower_32_bits(addr));
+ iproc_msi_write_reg(msi, IPROC_MSI_PAGE_UPPER, i,
+ upper_32_bits(addr));
+ }
+
+ for (eq = 0; eq < msi->nr_irqs; eq++) {
+ /* enable MSI event queue */
+ val = IPROC_MSI_INTR_EN | IPROC_MSI_INT_N_EVENT |
+ IPROC_MSI_EQ_EN;
+ iproc_msi_write_reg(msi, IPROC_MSI_CTRL, eq, val);
+
+ /*
+ * Some legacy platforms require the MSI interrupt enable
+ * register to be set explicitly
+ */
+ if (msi->has_inten_reg) {
+ val = iproc_msi_read_reg(msi, IPROC_MSI_INTS_EN, eq);
+ val |= BIT(eq);
+ iproc_msi_write_reg(msi, IPROC_MSI_INTS_EN, eq, val);
+ }
+ }
+}
+
+static void iproc_msi_disable(struct iproc_msi *msi)
+{
+ u32 eq, val;
+
+ for (eq = 0; eq < msi->nr_irqs; eq++) {
+ if (msi->has_inten_reg) {
+ val = iproc_msi_read_reg(msi, IPROC_MSI_INTS_EN, eq);
+ val &= ~BIT(eq);
+ iproc_msi_write_reg(msi, IPROC_MSI_INTS_EN, eq, val);
+ }
+
+ val = iproc_msi_read_reg(msi, IPROC_MSI_CTRL, eq);
+ val &= ~(IPROC_MSI_INTR_EN | IPROC_MSI_INT_N_EVENT |
+ IPROC_MSI_EQ_EN);
+ iproc_msi_write_reg(msi, IPROC_MSI_CTRL, eq, val);
+ }
+}
+
+static int iproc_msi_alloc_domains(struct device_node *node,
+ struct iproc_msi *msi)
+{
+ msi->inner_domain = irq_domain_add_linear(NULL, msi->nr_msi_vecs,
+ &msi_domain_ops, msi);
+ if (!msi->inner_domain)
+ return -ENOMEM;
+
+ msi->msi_domain = pci_msi_create_irq_domain(of_node_to_fwnode(node),
+ &iproc_msi_domain_info,
+ msi->inner_domain);
+ if (!msi->msi_domain) {
+ irq_domain_remove(msi->inner_domain);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static void iproc_msi_free_domains(struct iproc_msi *msi)
+{
+ if (msi->msi_domain)
+ irq_domain_remove(msi->msi_domain);
+
+ if (msi->inner_domain)
+ irq_domain_remove(msi->inner_domain);
+}
+
+static int iproc_msi_irq_setup(struct iproc_msi *msi, unsigned int cpu)
+{
+ int i, ret;
+ cpumask_var_t mask;
+ struct iproc_pcie *pcie = msi->pcie;
+
+ for (i = cpu; i < msi->nr_irqs; i += msi->nr_cpus) {
+ irq_set_chained_handler_and_data(msi->grps[i].gic_irq,
+ iproc_msi_handler,
+ &msi->grps[i]);
+ /* dedicate GIC interrupt to each CPU core */
+ if (alloc_cpumask_var(&mask, GFP_KERNEL)) {
+ cpumask_clear(mask);
+ cpumask_set_cpu(cpu, mask);
+ ret = irq_set_affinity(msi->grps[i].gic_irq, mask);
+ if (ret)
+ dev_err(pcie->dev,
+ "failed to set affinity for IRQ%d\n",
+ msi->grps[i].gic_irq);
+ free_cpumask_var(mask);
+ } else {
+ dev_err(pcie->dev, "failed to alloc CPU mask\n");
+ ret = -EINVAL;
+ }
+
+ if (ret) {
+ irq_set_chained_handler_and_data(msi->grps[i].gic_irq,
+ NULL, NULL);
+ return ret;
What happens to interrupts you've already configured? I'd expect a full
rollback.
Yeah in the error case, need to roll back all previously configured irq
by the time we exit this function. Will fix!
+ }
+ }
+
+ return 0;
+}
+
+static void iproc_msi_irq_free(struct iproc_msi *msi, unsigned int cpu)
+{
+ int i;
+
+ for (i = cpu; i < msi->nr_irqs; i += msi->nr_cpus) {
+ irq_set_chained_handler_and_data(msi->grps[i].gic_irq,
+ NULL, NULL);
+ }
+}
+
+int iproc_msi_init(struct iproc_pcie *pcie, struct device_node *node)
+{
+ struct iproc_msi *msi;
+ int i, ret;
+ unsigned int cpu;
+
+ if (!of_device_is_compatible(node, "brcm,iproc-msi"))
+ return -ENODEV;
+
+ if (!of_find_property(node, "msi-controller", NULL))
+ return -ENODEV;
+
+ if (pcie->msi)
+ return -EBUSY;
+
+ msi = devm_kzalloc(pcie->dev, sizeof(*msi), GFP_KERNEL);
+ if (!msi)
+ return -ENOMEM;
+
+ msi->pcie = pcie;
+ pcie->msi = msi;
+ mutex_init(&msi->bitmap_lock);
+ msi->nr_cpus = num_possible_cpus();
+
+ switch (pcie->type) {
+ case IPROC_PCIE_PAXB:
+ msi->reg_offsets = iproc_msi_reg_paxb;
+ break;
+ case IPROC_PCIE_PAXC:
+ msi->reg_offsets = iproc_msi_reg_paxc;
+ break;
+ default:
+ dev_err(pcie->dev, "incompatible iProc PCIe interface\n");
+ return -EINVAL;
+ }
+
+ if (of_find_property(node, "brcm,pcie-msi-inten", NULL))
+ msi->has_inten_reg = true;
+
+ ret = of_property_read_u32(node, "brcm,num-eq-region",
+ &msi->nr_eq_region);
+ if (ret || !msi->nr_eq_region)
+ msi->nr_eq_region = 1;
+
+ ret = of_property_read_u32(node, "brcm,num-msi-msg-region",
+ &msi->nr_msi_region);
+ if (ret || !msi->nr_msi_region)
+ msi->nr_msi_region = 1;
+
+ msi->nr_irqs = of_irq_count(node);
+ if (!msi->nr_irqs) {
+ dev_err(pcie->dev, "found no MSI GIC interrupt\n");
+ return -ENODEV;
+ }
+ if (msi->nr_irqs > NR_HW_IRQS) {
+ dev_warn(pcie->dev, "too many MSI GIC interrupts defined %d\n",
+ msi->nr_irqs);
+ msi->nr_irqs = NR_HW_IRQS;
+ }
+
+ msi->nr_msi_vecs = msi->nr_irqs * EQ_LEN;
+ msi->bitmap = devm_kcalloc(pcie->dev, BITS_TO_LONGS(msi->nr_msi_vecs),
+ sizeof(*msi->bitmap), GFP_KERNEL);
+ if (!msi->bitmap)
+ return -ENOMEM;
+
+ msi->grps = devm_kcalloc(pcie->dev, msi->nr_irqs, sizeof(*msi->grps),
+ GFP_KERNEL);
+ if (!msi->grps)
+ return -ENOMEM;
+
+ for (i = 0; i < msi->nr_irqs; i++) {
+ unsigned int irq = irq_of_parse_and_map(node, i);
+
+ if (!irq) {
+ dev_err(pcie->dev, "unable to parse/map interrupt\n");
+ return -ENODEV;
+ }
+ msi->grps[i].gic_irq = irq;
+ msi->grps[i].msi = msi;
+ msi->grps[i].eq = i;
+ }
+
+ /* reserve memory for MSI event queue */
+ msi->eq_cpu = dma_alloc_coherent(pcie->dev,
+ msi->nr_eq_region * EQ_MEM_REGION_SIZE,
+ &msi->eq_dma, GFP_KERNEL);
Do you need to zero that memory? Or is the HW happy with whatever will
be there?
It seems to work fine. But you are right, it's much safer to zero the
memory since the PCIe controller could be using the upper 16-bit of each
word-sized entry in the event queue.
+ if (!msi->eq_cpu)
+ return -ENOMEM;
+
+ /* reserve memory for MSI posted writes */
+ msi->msi_cpu = dma_alloc_coherent(pcie->dev,
+ msi->nr_msi_region * MSI_MEM_REGION_SIZE,
+ &msi->msi_dma, GFP_KERNEL);
Same here. Also, what is the exact purpose of that memory? You have a
coherent mapping with the CPU, but you never read from it. So what's
the point?
Yeah I guess I can change this back to kmalloc since coherent memory is
a scarce resource, and the CPU does not need to access the memory, so
there's no cache issue.
I know I have not answered the first part of your question. Let me do
some experiments first and I'll get back to you on that, :)
+ if (!msi->msi_cpu) {
+ ret = -ENOMEM;
+ goto free_eq_dma;
+ }
+
+ ret = iproc_msi_alloc_domains(node, msi);
+ if (ret) {
+ dev_err(pcie->dev, "failed to create MSI domains\n");
+ goto free_msi_dma;
+ }
+
+ for_each_online_cpu(cpu) {
+ ret = iproc_msi_irq_setup(msi, cpu);
+ if (ret)
+ goto free_msi_irq;
+ }
+
+ iproc_msi_enable(msi);
+
+ return 0;
+
+free_msi_irq:
+ for_each_online_cpu(cpu)
+ iproc_msi_irq_free(msi, cpu);
+ iproc_msi_free_domains(msi);
+
+free_msi_dma:
+ dma_free_coherent(pcie->dev, msi->nr_msi_region * MSI_MEM_REGION_SIZE,
+ msi->msi_cpu, msi->msi_dma);
+free_eq_dma:
+ dma_free_coherent(pcie->dev, msi->nr_eq_region * EQ_MEM_REGION_SIZE,
+ msi->eq_cpu, msi->eq_dma);
+ pcie->msi = NULL;
+ return ret;
+}
+EXPORT_SYMBOL(iproc_msi_init);
[...]
Thanks,
M.
Thanks, Marc!
Ray
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