linux/drivers/pci/controller/pcie-altera-msi.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Altera PCIe MSI support
   4 *
   5 * Author: Ley Foon Tan <lftan@altera.com>
   6 *
   7 * Copyright Altera Corporation (C) 2013-2015. All rights reserved
   8 */
   9
  10#include <linux/interrupt.h>
  11#include <linux/irqchip/chained_irq.h>
  12#include <linux/init.h>
  13#include <linux/module.h>
  14#include <linux/msi.h>
  15#include <linux/of_address.h>
  16#include <linux/of_irq.h>
  17#include <linux/of_pci.h>
  18#include <linux/pci.h>
  19#include <linux/platform_device.h>
  20#include <linux/slab.h>
  21
  22#define MSI_STATUS              0x0
  23#define MSI_ERROR               0x4
  24#define MSI_INTMASK             0x8
  25
  26#define MAX_MSI_VECTORS         32
  27
  28struct altera_msi {
  29        DECLARE_BITMAP(used, MAX_MSI_VECTORS);
  30        struct mutex            lock;   /* protect "used" bitmap */
  31        struct platform_device  *pdev;
  32        struct irq_domain       *msi_domain;
  33        struct irq_domain       *inner_domain;
  34        void __iomem            *csr_base;
  35        void __iomem            *vector_base;
  36        phys_addr_t             vector_phy;
  37        u32                     num_of_vectors;
  38        int                     irq;
  39};
  40
  41static inline void msi_writel(struct altera_msi *msi, const u32 value,
  42                              const u32 reg)
  43{
  44        writel_relaxed(value, msi->csr_base + reg);
  45}
  46
  47static inline u32 msi_readl(struct altera_msi *msi, const u32 reg)
  48{
  49        return readl_relaxed(msi->csr_base + reg);
  50}
  51
  52static void altera_msi_isr(struct irq_desc *desc)
  53{
  54        struct irq_chip *chip = irq_desc_get_chip(desc);
  55        struct altera_msi *msi;
  56        unsigned long status;
  57        u32 bit;
  58        u32 virq;
  59
  60        chained_irq_enter(chip, desc);
  61        msi = irq_desc_get_handler_data(desc);
  62
  63        while ((status = msi_readl(msi, MSI_STATUS)) != 0) {
  64                for_each_set_bit(bit, &status, msi->num_of_vectors) {
  65                        /* Dummy read from vector to clear the interrupt */
  66                        readl_relaxed(msi->vector_base + (bit * sizeof(u32)));
  67
  68                        virq = irq_find_mapping(msi->inner_domain, bit);
  69                        if (virq)
  70                                generic_handle_irq(virq);
  71                        else
  72                                dev_err(&msi->pdev->dev, "unexpected MSI\n");
  73                }
  74        }
  75
  76        chained_irq_exit(chip, desc);
  77}
  78
  79static struct irq_chip altera_msi_irq_chip = {
  80        .name = "Altera PCIe MSI",
  81        .irq_mask = pci_msi_mask_irq,
  82        .irq_unmask = pci_msi_unmask_irq,
  83};
  84
  85static struct msi_domain_info altera_msi_domain_info = {
  86        .flags  = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
  87                     MSI_FLAG_PCI_MSIX),
  88        .chip   = &altera_msi_irq_chip,
  89};
  90
  91static void altera_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
  92{
  93        struct altera_msi *msi = irq_data_get_irq_chip_data(data);
  94        phys_addr_t addr = msi->vector_phy + (data->hwirq * sizeof(u32));
  95
  96        msg->address_lo = lower_32_bits(addr);
  97        msg->address_hi = upper_32_bits(addr);
  98        msg->data = data->hwirq;
  99
 100        dev_dbg(&msi->pdev->dev, "msi#%d address_hi %#x address_lo %#x\n",
 101                (int)data->hwirq, msg->address_hi, msg->address_lo);
 102}
 103
 104static int altera_msi_set_affinity(struct irq_data *irq_data,
 105                                   const struct cpumask *mask, bool force)
 106{
 107         return -EINVAL;
 108}
 109
 110static struct irq_chip altera_msi_bottom_irq_chip = {
 111        .name                   = "Altera MSI",
 112        .irq_compose_msi_msg    = altera_compose_msi_msg,
 113        .irq_set_affinity       = altera_msi_set_affinity,
 114};
 115
 116static int altera_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 117                                   unsigned int nr_irqs, void *args)
 118{
 119        struct altera_msi *msi = domain->host_data;
 120        unsigned long bit;
 121        u32 mask;
 122
 123        WARN_ON(nr_irqs != 1);
 124        mutex_lock(&msi->lock);
 125
 126        bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
 127        if (bit >= msi->num_of_vectors) {
 128                mutex_unlock(&msi->lock);
 129                return -ENOSPC;
 130        }
 131
 132        set_bit(bit, msi->used);
 133
 134        mutex_unlock(&msi->lock);
 135
 136        irq_domain_set_info(domain, virq, bit, &altera_msi_bottom_irq_chip,
 137                            domain->host_data, handle_simple_irq,
 138                            NULL, NULL);
 139
 140        mask = msi_readl(msi, MSI_INTMASK);
 141        mask |= 1 << bit;
 142        msi_writel(msi, mask, MSI_INTMASK);
 143
 144        return 0;
 145}
 146
 147static void altera_irq_domain_free(struct irq_domain *domain,
 148                                   unsigned int virq, unsigned int nr_irqs)
 149{
 150        struct irq_data *d = irq_domain_get_irq_data(domain, virq);
 151        struct altera_msi *msi = irq_data_get_irq_chip_data(d);
 152        u32 mask;
 153
 154        mutex_lock(&msi->lock);
 155
 156        if (!test_bit(d->hwirq, msi->used)) {
 157                dev_err(&msi->pdev->dev, "trying to free unused MSI#%lu\n",
 158                        d->hwirq);
 159        } else {
 160                __clear_bit(d->hwirq, msi->used);
 161                mask = msi_readl(msi, MSI_INTMASK);
 162                mask &= ~(1 << d->hwirq);
 163                msi_writel(msi, mask, MSI_INTMASK);
 164        }
 165
 166        mutex_unlock(&msi->lock);
 167}
 168
 169static const struct irq_domain_ops msi_domain_ops = {
 170        .alloc  = altera_irq_domain_alloc,
 171        .free   = altera_irq_domain_free,
 172};
 173
 174static int altera_allocate_domains(struct altera_msi *msi)
 175{
 176        struct fwnode_handle *fwnode = of_node_to_fwnode(msi->pdev->dev.of_node);
 177
 178        msi->inner_domain = irq_domain_add_linear(NULL, msi->num_of_vectors,
 179                                             &msi_domain_ops, msi);
 180        if (!msi->inner_domain) {
 181                dev_err(&msi->pdev->dev, "failed to create IRQ domain\n");
 182                return -ENOMEM;
 183        }
 184
 185        msi->msi_domain = pci_msi_create_irq_domain(fwnode,
 186                                &altera_msi_domain_info, msi->inner_domain);
 187        if (!msi->msi_domain) {
 188                dev_err(&msi->pdev->dev, "failed to create MSI domain\n");
 189                irq_domain_remove(msi->inner_domain);
 190                return -ENOMEM;
 191        }
 192
 193        return 0;
 194}
 195
 196static void altera_free_domains(struct altera_msi *msi)
 197{
 198        irq_domain_remove(msi->msi_domain);
 199        irq_domain_remove(msi->inner_domain);
 200}
 201
 202static int altera_msi_remove(struct platform_device *pdev)
 203{
 204        struct altera_msi *msi = platform_get_drvdata(pdev);
 205
 206        msi_writel(msi, 0, MSI_INTMASK);
 207        irq_set_chained_handler_and_data(msi->irq, NULL, NULL);
 208
 209        altera_free_domains(msi);
 210
 211        platform_set_drvdata(pdev, NULL);
 212        return 0;
 213}
 214
 215static int altera_msi_probe(struct platform_device *pdev)
 216{
 217        struct altera_msi *msi;
 218        struct device_node *np = pdev->dev.of_node;
 219        struct resource *res;
 220        int ret;
 221
 222        msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
 223                           GFP_KERNEL);
 224        if (!msi)
 225                return -ENOMEM;
 226
 227        mutex_init(&msi->lock);
 228        msi->pdev = pdev;
 229
 230        msi->csr_base = devm_platform_ioremap_resource_byname(pdev, "csr");
 231        if (IS_ERR(msi->csr_base)) {
 232                dev_err(&pdev->dev, "failed to map csr memory\n");
 233                return PTR_ERR(msi->csr_base);
 234        }
 235
 236        res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
 237                                           "vector_slave");
 238        msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
 239        if (IS_ERR(msi->vector_base))
 240                return PTR_ERR(msi->vector_base);
 241
 242        msi->vector_phy = res->start;
 243
 244        if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
 245                dev_err(&pdev->dev, "failed to parse the number of vectors\n");
 246                return -EINVAL;
 247        }
 248
 249        ret = altera_allocate_domains(msi);
 250        if (ret)
 251                return ret;
 252
 253        msi->irq = platform_get_irq(pdev, 0);
 254        if (msi->irq < 0) {
 255                ret = msi->irq;
 256                goto err;
 257        }
 258
 259        irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
 260        platform_set_drvdata(pdev, msi);
 261
 262        return 0;
 263
 264err:
 265        altera_msi_remove(pdev);
 266        return ret;
 267}
 268
 269static const struct of_device_id altera_msi_of_match[] = {
 270        { .compatible = "altr,msi-1.0", NULL },
 271        { },
 272};
 273
 274static struct platform_driver altera_msi_driver = {
 275        .driver = {
 276                .name = "altera-msi",
 277                .of_match_table = altera_msi_of_match,
 278        },
 279        .probe = altera_msi_probe,
 280        .remove = altera_msi_remove,
 281};
 282
 283static int __init altera_msi_init(void)
 284{
 285        return platform_driver_register(&altera_msi_driver);
 286}
 287
 288static void __exit altera_msi_exit(void)
 289{
 290        platform_driver_unregister(&altera_msi_driver);
 291}
 292
 293subsys_initcall(altera_msi_init);
 294MODULE_DEVICE_TABLE(of, altera_msi_of_match);
 295module_exit(altera_msi_exit);
 296MODULE_LICENSE("GPL v2");
 297