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[PATCH v2 10/16] xen/riscv: imsic_init() implementation



imsic_init() is introduced to parse device tree node, which has the following
bindings [2], and based on the parsed information update IMSIC configuration
which is stored in imsic_cfg.

The following helpers are introduces for imsic_init() usage:
  - imsic_parse_node() parses IMSIC node from DTS
  - imsic_get_parent_cpuid() returns the hart ( CPU ) ID of the given device
    tree node.

This patch is based on the code from [1].

Since Microchip originally developed imsic.{c,h}, an internal discussion with
them led to the decision to use the MIT license.

[1] 
https://gitlab.com/xen-project/people/olkur/xen/-/commit/0b1a94f2bc3bb1a81cd26bb75f0bf578f84cb4d4
[2] 
https://elixir.bootlin.com/linux/v6.12/source/Documentation/devicetree/bindings/interrupt-controller/riscv,imsics.yaml

Co-developed-by: Romain Caritey <Romain.Caritey@xxxxxxxxxxxxx>
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in V2:
 - Drop years in copyrights.
 - s/riscv_of_processor_hartid/dt_processor_cpuid.
 - s/imsic_get_parent_hartid/imsic_get_parent_cpuid.
   Rename argument hartid to cpuid.
   Make node argument const.
   Return res instead of -EINVAL for the failure case of dt_processor_cpuid().
   Drop local variable hart and use cpuid argument instead.
   Drop useless return res;
 - imsic_parse_node() changes:
   - Make node argument const.
   - Check the return value of dt_property_read_u32() directly instead of
     saving it to rc variable.
   - Update tmp usage, use short form "-=".
   - Update a check (imsic_cfg.nr_ids >= IMSIC_MAX_ID) to (imsic_cfg.nr_ids > 
IMSIC_MAX_ID)
     as IMSIC_MAX_ID is changed to maximum valid value, not just the firsr 
out-of-range.
   - Use `rc` to return value instead of explicitly use -EINVAL.
   - Use do {} while() to find number of MMIO register sets.
 - Set IMSIC_MAX_ID to 2047 (maximum possible IRQ number).
 - imsic_init() changes:
   - Use unsigned int in for's expression1.
   - s/xfree/XFEE.
   - Allocate msi and cpus array dynamically.
 - Drop forward declaration before declaration of imsic_get_config() in 
asm/imsic.h
   as it is not used as parameter type.
 - Align declaration of imisic_init with defintion.
 - s/harts/cpus in imisic_mmios.
   Also, change type from bool harts[NR_CPUS] to unsigned long *cpus.
 - Allocate msi member of imsic_config dynamically to save some memory.
 - Code style fixes.
 - Update the commit message.
---
 xen/arch/riscv/Makefile            |   1 +
 xen/arch/riscv/imsic.c             | 286 +++++++++++++++++++++++++++++
 xen/arch/riscv/include/asm/imsic.h |  65 +++++++
 3 files changed, 352 insertions(+)
 create mode 100644 xen/arch/riscv/imsic.c
 create mode 100644 xen/arch/riscv/include/asm/imsic.h

diff --git a/xen/arch/riscv/Makefile b/xen/arch/riscv/Makefile
index a1c145c506..e2b8aa42c8 100644
--- a/xen/arch/riscv/Makefile
+++ b/xen/arch/riscv/Makefile
@@ -2,6 +2,7 @@ obj-y += aplic.o
 obj-y += cpufeature.o
 obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
 obj-y += entry.o
+obj-y += imsic.o
 obj-y += intc.o
 obj-y += irq.o
 obj-y += mm.o
diff --git a/xen/arch/riscv/imsic.c b/xen/arch/riscv/imsic.c
new file mode 100644
index 0000000000..43d0c92cbd
--- /dev/null
+++ b/xen/arch/riscv/imsic.c
@@ -0,0 +1,286 @@
+/* SPDX-License-Identifier: MIT */
+
+/*
+ * xen/arch/riscv/imsic.c
+ *
+ * RISC-V Incoming MSI Controller support
+ *
+ * (c) Microchip Technology Inc.
+ * (c) Vates
+ */
+
+#include <xen/const.h>
+#include <xen/device_tree.h>
+#include <xen/errno.h>
+#include <xen/init.h>
+#include <xen/macros.h>
+#include <xen/xmalloc.h>
+
+#include <asm/imsic.h>
+
+static struct imsic_config imsic_cfg;
+
+/* Callers aren't expected to changed imsic_cfg so return const. */
+const struct imsic_config *imsic_get_config(void)
+{
+    return &imsic_cfg;
+}
+
+static int __init imsic_get_parent_cpuid(const struct dt_device_node *node,
+                                         unsigned int index,
+                                         unsigned long *cpuid)
+{
+    int res;
+    struct dt_phandle_args args;
+
+    res = dt_parse_phandle_with_args(node, "interrupts-extended",
+                                     "#interrupt-cells", index, &args);
+    if ( !res )
+        res = dt_processor_cpuid(args.np->parent, cpuid);
+
+    return res;
+}
+
+static int imsic_parse_node(const struct dt_device_node *node,
+                            unsigned int *nr_parent_irqs)
+{
+    int rc;
+    unsigned int tmp;
+    paddr_t base_addr;
+
+    /* Find number of parent interrupts */
+    *nr_parent_irqs = dt_number_of_irq(node);
+    if ( !*nr_parent_irqs )
+    {
+        printk(XENLOG_ERR "%s: no parent irqs available\n", node->name);
+        return -ENOENT;
+    }
+
+    if ( !dt_property_read_u32(node, "riscv,guest-index-bits",
+                               &imsic_cfg.guest_index_bits) )
+        imsic_cfg.guest_index_bits = 0;
+    tmp = BITS_PER_LONG - IMSIC_MMIO_PAGE_SHIFT;
+    if ( tmp < imsic_cfg.guest_index_bits )
+    {
+        printk(XENLOG_ERR "%s: guest index bits too big\n", node->name);
+        return -ENOENT;
+    }
+
+    /* Find number of HART index bits */
+    if ( !dt_property_read_u32(node, "riscv,hart-index-bits",
+                               &imsic_cfg.hart_index_bits) )
+    {
+        /* Assume default value */
+        imsic_cfg.hart_index_bits = fls(*nr_parent_irqs);
+        if ( BIT(imsic_cfg.hart_index_bits, UL) < *nr_parent_irqs )
+            imsic_cfg.hart_index_bits++;
+    }
+    tmp -= imsic_cfg.guest_index_bits;
+    if ( tmp < imsic_cfg.hart_index_bits )
+    {
+        printk(XENLOG_ERR "%s: HART index bits too big\n", node->name);
+        return -ENOENT;
+    }
+
+    /* Find number of group index bits */
+    if ( !dt_property_read_u32(node, "riscv,group-index-bits",
+                               &imsic_cfg.group_index_bits) )
+        imsic_cfg.group_index_bits = 0;
+    tmp -= imsic_cfg.hart_index_bits;
+    if ( tmp < imsic_cfg.group_index_bits )
+    {
+        printk(XENLOG_ERR "%s: group index bits too big\n", node->name);
+        return -ENOENT;
+    }
+
+    /* Find first bit position of group index */
+    tmp = IMSIC_MMIO_PAGE_SHIFT * 2;
+    if ( !dt_property_read_u32(node, "riscv,group-index-shift",
+                               &imsic_cfg.group_index_shift) )
+        imsic_cfg.group_index_shift = tmp;
+    if ( imsic_cfg.group_index_shift < tmp )
+    {
+        printk(XENLOG_ERR "%s: group index shift too small\n", node->name);
+        return -ENOENT;
+    }
+    tmp = imsic_cfg.group_index_bits + imsic_cfg.group_index_shift - 1;
+    if ( tmp >= BITS_PER_LONG )
+    {
+        printk(XENLOG_ERR "%s: group index shift too big\n", node->name);
+        return -EINVAL;
+    }
+
+    /* Find number of interrupt identities */
+    if ( !dt_property_read_u32(node, "riscv,num-ids", &imsic_cfg.nr_ids) )
+    {
+        printk(XENLOG_ERR "%s: number of interrupt identities not found\n",
+               node->name);
+        return -ENOENT;
+    }
+
+    if ( (imsic_cfg.nr_ids < IMSIC_MIN_ID) ||
+         (imsic_cfg.nr_ids > IMSIC_MAX_ID) ||
+         ((imsic_cfg.nr_ids & IMSIC_MIN_ID) != IMSIC_MIN_ID) )
+    {
+        printk(XENLOG_ERR "%s: invalid number of interrupt identities\n",
+               node->name);
+        return -EINVAL;
+    }
+
+    /* Compute base address */
+    imsic_cfg.nr_mmios = 0;
+    rc = dt_device_get_address(node, imsic_cfg.nr_mmios, &base_addr, NULL);
+    if ( rc )
+    {
+        printk(XENLOG_ERR "%s: first MMIO resource not found\n", node->name);
+        return rc;
+    }
+
+    imsic_cfg.base_addr = base_addr;
+    imsic_cfg.base_addr &= ~(BIT(imsic_cfg.guest_index_bits +
+                           imsic_cfg.hart_index_bits +
+                           IMSIC_MMIO_PAGE_SHIFT, UL) - 1);
+    imsic_cfg.base_addr &= ~((BIT(imsic_cfg.group_index_bits, UL) - 1) <<
+                           imsic_cfg.group_index_shift);
+
+    /* Find number of MMIO register sets */
+    do {
+        imsic_cfg.nr_mmios++;
+    } while ( !dt_device_get_address(node, imsic_cfg.nr_mmios, &base_addr, 
NULL) );
+
+    return 0;
+}
+
+int __init imsic_init(const struct dt_device_node *node)
+{
+    int rc;
+    unsigned long reloff, cpuid;
+    uint32_t nr_parent_irqs, index, nr_handlers = 0;
+    paddr_t base_addr;
+    unsigned int nr_mmios;
+
+    /* Parse IMSIC node */
+    rc = imsic_parse_node(node, &nr_parent_irqs);
+    if ( rc )
+        return rc;
+
+    nr_mmios = imsic_cfg.nr_mmios;
+
+    /* Allocate MMIO resource array */
+    imsic_cfg.mmios = xzalloc_array(struct imsic_mmios, nr_mmios);
+    if ( !imsic_cfg.mmios )
+        return -ENOMEM;
+
+    imsic_cfg.msi = xzalloc_array(struct imsic_msi, nr_parent_irqs);
+    if ( !imsic_cfg.msi )
+        return -ENOMEM;
+
+    /* Check MMIO register sets */
+    for ( unsigned int i = 0; i < nr_mmios; i++ )
+    {
+        imsic_cfg.mmios[i].cpus = xzalloc_array(unsigned long,
+                                                BITS_TO_LONGS(nr_parent_irqs));
+        if ( !imsic_cfg.mmios[i].cpus )
+            return -ENOMEM;
+
+        rc = dt_device_get_address(node, i, &imsic_cfg.mmios[i].base_addr,
+                                   &imsic_cfg.mmios[i].size);
+        if ( rc )
+        {
+            printk(XENLOG_ERR "%s:  unable to parse MMIO regset %d\n",
+                   node->name, i);
+            goto imsic_init_err;
+        }
+
+        base_addr = imsic_cfg.mmios[i].base_addr;
+        base_addr &= ~(BIT(imsic_cfg.guest_index_bits +
+                     imsic_cfg.hart_index_bits +
+                     IMSIC_MMIO_PAGE_SHIFT, UL) - 1);
+        base_addr &= ~((BIT(imsic_cfg.group_index_bits, UL) - 1) <<
+                     imsic_cfg.group_index_shift);
+        if ( base_addr != imsic_cfg.base_addr )
+        {
+            rc = -EINVAL;
+            printk(XENLOG_ERR "%s: address mismatch for regset %d\n",
+                   node->name, i);
+            goto imsic_init_err;
+        }
+    }
+
+    /* Configure handlers for target CPUs */
+    for ( unsigned int i = 0; i < nr_parent_irqs; i++ )
+    {
+        rc = imsic_get_parent_cpuid(node, i, &cpuid);
+        if ( rc )
+        {
+            printk(XENLOG_WARNING "%s: cpu ID for parent irq%d not found\n",
+                   node->name, i);
+            continue;
+        }
+
+        if ( cpuid >= num_possible_cpus() )
+        {
+            printk(XENLOG_WARNING "%s: unsupported cpu ID=%lu for parent 
irq%d\n",
+                   node->name, cpuid, i);
+            continue;
+        }
+
+        /* Find MMIO location of MSI page */
+        index = nr_mmios;
+        reloff = i * BIT(imsic_cfg.guest_index_bits, UL) * IMSIC_MMIO_PAGE_SZ;
+        for ( unsigned int j = 0; nr_mmios; j++ )
+        {
+            if ( reloff < imsic_cfg.mmios[j].size )
+            {
+                index = j;
+                break;
+            }
+
+            /*
+             * MMIO region size may not be aligned to
+             * BIT(global->guest_index_bits) * IMSIC_MMIO_PAGE_SZ
+             * if holes are present.
+             */
+            reloff -= ROUNDUP(imsic_cfg.mmios[j].size,
+                BIT(imsic_cfg.guest_index_bits, UL) * IMSIC_MMIO_PAGE_SZ);
+        }
+
+        if ( index >= nr_mmios )
+        {
+            printk(XENLOG_WARNING "%s: MMIO not found for parent irq%d\n",
+                   node->name, i);
+            continue;
+        }
+
+        if ( !IS_ALIGNED(imsic_cfg.msi[cpuid].base_addr + reloff, PAGE_SIZE) )
+        {
+            printk(XENLOG_WARNING "%s: MMIO address 0x%lx is not aligned on a 
page\n",
+                   node->name, imsic_cfg.msi[cpuid].base_addr + reloff);
+            imsic_cfg.msi[cpuid].offset = 0;
+            imsic_cfg.msi[cpuid].base_addr = 0;
+            continue;
+        }
+
+        bitmap_set(imsic_cfg.mmios[index].cpus, cpuid, 1);
+        imsic_cfg.msi[cpuid].base_addr = imsic_cfg.mmios[index].base_addr;
+        imsic_cfg.msi[cpuid].offset = reloff;
+        nr_handlers++;
+    }
+
+    if ( !nr_handlers )
+    {
+        printk(XENLOG_ERR "%s: No CPU handlers found\n", node->name);
+        rc = -ENODEV;
+        goto imsic_init_err;
+    }
+
+    return 0;
+
+ imsic_init_err:
+    for ( unsigned int i = 0; i < nr_mmios; i++ )
+        XFREE(imsic_cfg.mmios[i].cpus);
+    XFREE(imsic_cfg.mmios);
+    XFREE(imsic_cfg.msi);
+
+    return rc;
+}
diff --git a/xen/arch/riscv/include/asm/imsic.h 
b/xen/arch/riscv/include/asm/imsic.h
new file mode 100644
index 0000000000..ed51cac780
--- /dev/null
+++ b/xen/arch/riscv/include/asm/imsic.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: MIT */
+
+/*
+ * xen/arch/riscv/imsic.h
+ *
+ * RISC-V Incoming MSI Controller support
+ *
+ * (c) 2023 Microchip Technology Inc.
+ */
+
+#ifndef ASM__RISCV__IMSIC_H
+#define ASM__RISCV__IMSIC_H
+
+#include <xen/types.h>
+
+#define IMSIC_MMIO_PAGE_SHIFT   12
+#define IMSIC_MMIO_PAGE_SZ      (1UL << IMSIC_MMIO_PAGE_SHIFT)
+
+#define IMSIC_MIN_ID            63
+#define IMSIC_MAX_ID            2047
+
+struct imsic_msi {
+    paddr_t base_addr;
+    unsigned long offset;
+};
+
+struct imsic_mmios {
+    paddr_t base_addr;
+    unsigned long size;
+    unsigned long *cpus;
+};
+
+struct imsic_config {
+    /* base address */
+    paddr_t base_addr;
+
+    /* Bits representing Guest index, HART index, and Group index */
+    unsigned int guest_index_bits;
+    unsigned int hart_index_bits;
+    unsigned int group_index_bits;
+    unsigned int group_index_shift;
+
+    /* imsic phandle */
+    unsigned int phandle;
+
+    /* number of parent irq */
+    unsigned int nr_parent_irqs;
+
+    /* number off interrupt identities */
+    unsigned int nr_ids;
+
+    /* mmios */
+    unsigned int nr_mmios;
+    struct imsic_mmios *mmios;
+
+    /* MSI */
+    struct imsic_msi *msi;
+};
+
+struct dt_device_node;
+int imsic_init(const struct dt_device_node *node);
+
+const struct imsic_config *imsic_get_config(void);
+
+#endif /* ASM__RISCV__IMSIC_H */
-- 
2.49.0




 


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