drivers/pci/controller/pcie-altera-msi.c

   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/irqdomain.h>
  13 #include <linux/init.h>
  14 #include <linux/module.h>
  15 #include <linux/msi.h>
  16 #include <linux/of_address.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
  28 struct 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
  41 static 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
  47 static inline u32 msi_readl(struct altera_msi *msi, const u32 reg)
  48 {
  49         return readl_relaxed(msi->csr_base + reg);
  50 }
  51
  52 static 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         int ret;
  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                         ret = generic_handle_domain_irq(msi->inner_domain, bit);
  69                         if (ret)
  70                                 dev_err_ratelimited(&msi->pdev->dev, "unexpected MSI\n");
  71                 }
  72         }
  73
  74         chained_irq_exit(chip, desc);
  75 }
  76
  77 static struct irq_chip altera_msi_irq_chip = {
  78         .name = "Altera PCIe MSI",
  79         .irq_mask = pci_msi_mask_irq,
  80         .irq_unmask = pci_msi_unmask_irq,
  81 };
  82
  83 static struct msi_domain_info altera_msi_domain_info = {
  84         .flags  = MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
  85                   MSI_FLAG_NO_AFFINITY | MSI_FLAG_PCI_MSIX,
  86         .chip   = &altera_msi_irq_chip,
  87 };
  88
  89 static void altera_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
  90 {
  91         struct altera_msi *msi = irq_data_get_irq_chip_data(data);
  92         phys_addr_t addr = msi->vector_phy + (data->hwirq * sizeof(u32));
  93
  94         msg->address_lo = lower_32_bits(addr);
  95         msg->address_hi = upper_32_bits(addr);
  96         msg->data = data->hwirq;
  97
  98         dev_dbg(&msi->pdev->dev, "msi#%d address_hi %#x address_lo %#x\n",
  99                 (int)data->hwirq, msg->address_hi, msg->address_lo);
 100 }
 101
 102 static struct irq_chip altera_msi_bottom_irq_chip = {
 103         .name                   = "Altera MSI",
 104         .irq_compose_msi_msg    = altera_compose_msi_msg,
 105 };
 106
 107 static int altera_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 108                                    unsigned int nr_irqs, void *args)
 109 {
 110         struct altera_msi *msi = domain->host_data;
 111         unsigned long bit;
 112         u32 mask;
 113
 114         WARN_ON(nr_irqs != 1);
 115         mutex_lock(&msi->lock);
 116
 117         bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
 118         if (bit >= msi->num_of_vectors) {
 119                 mutex_unlock(&msi->lock);
 120                 return -ENOSPC;
 121         }
 122
 123         set_bit(bit, msi->used);
 124
 125         mutex_unlock(&msi->lock);
 126
 127         irq_domain_set_info(domain, virq, bit, &altera_msi_bottom_irq_chip,
 128                             domain->host_data, handle_simple_irq,
 129                             NULL, NULL);
 130
 131         mask = msi_readl(msi, MSI_INTMASK);
 132         mask |= 1 << bit;
 133         msi_writel(msi, mask, MSI_INTMASK);
 134
 135         return 0;
 136 }
 137
 138 static void altera_irq_domain_free(struct irq_domain *domain,
 139                                    unsigned int virq, unsigned int nr_irqs)
 140 {
 141         struct irq_data *d = irq_domain_get_irq_data(domain, virq);
 142         struct altera_msi *msi = irq_data_get_irq_chip_data(d);
 143         u32 mask;
 144
 145         mutex_lock(&msi->lock);
 146
 147         if (!test_bit(d->hwirq, msi->used)) {
 148                 dev_err(&msi->pdev->dev, "trying to free unused MSI#%lu\n",
 149                         d->hwirq);
 150         } else {
 151                 __clear_bit(d->hwirq, msi->used);
 152                 mask = msi_readl(msi, MSI_INTMASK);
 153                 mask &= ~(1 << d->hwirq);
 154                 msi_writel(msi, mask, MSI_INTMASK);
 155         }
 156
 157         mutex_unlock(&msi->lock);
 158 }
 159
 160 static const struct irq_domain_ops msi_domain_ops = {
 161         .alloc  = altera_irq_domain_alloc,
 162         .free   = altera_irq_domain_free,
 163 };
 164
 165 static int altera_allocate_domains(struct altera_msi *msi)
 166 {
 167         struct fwnode_handle *fwnode = of_node_to_fwnode(msi->pdev->dev.of_node);
 168
 169         msi->inner_domain = irq_domain_add_linear(NULL, msi->num_of_vectors,
 170                                              &msi_domain_ops, msi);
 171         if (!msi->inner_domain) {
 172                 dev_err(&msi->pdev->dev, "failed to create IRQ domain\n");
 173                 return -ENOMEM;
 174         }
 175
 176         msi->msi_domain = pci_msi_create_irq_domain(fwnode,
 177                                 &altera_msi_domain_info, msi->inner_domain);
 178         if (!msi->msi_domain) {
 179                 dev_err(&msi->pdev->dev, "failed to create MSI domain\n");
 180                 irq_domain_remove(msi->inner_domain);
 181                 return -ENOMEM;
 182         }
 183
 184         return 0;
 185 }
 186
 187 static void altera_free_domains(struct altera_msi *msi)
 188 {
 189         irq_domain_remove(msi->msi_domain);
 190         irq_domain_remove(msi->inner_domain);
 191 }
 192
 193 static void altera_msi_remove(struct platform_device *pdev)
 194 {
 195         struct altera_msi *msi = platform_get_drvdata(pdev);
 196
 197         msi_writel(msi, 0, MSI_INTMASK);
 198         irq_set_chained_handler_and_data(msi->irq, NULL, NULL);
 199
 200         altera_free_domains(msi);
 201
 202         platform_set_drvdata(pdev, NULL);
 203 }
 204
 205 static int altera_msi_probe(struct platform_device *pdev)
 206 {
 207         struct altera_msi *msi;
 208         struct device_node *np = pdev->dev.of_node;
 209         struct resource *res;
 210         int ret;
 211
 212         msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
 213                            GFP_KERNEL);
 214         if (!msi)
 215                 return -ENOMEM;
 216
 217         mutex_init(&msi->lock);
 218         msi->pdev = pdev;
 219
 220         msi->csr_base = devm_platform_ioremap_resource_byname(pdev, "csr");
 221         if (IS_ERR(msi->csr_base)) {
 222                 dev_err(&pdev->dev, "failed to map csr memory\n");
 223                 return PTR_ERR(msi->csr_base);
 224         }
 225
 226         res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
 227                                            "vector_slave");
 228         msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
 229         if (IS_ERR(msi->vector_base))
 230                 return PTR_ERR(msi->vector_base);
 231
 232         msi->vector_phy = res->start;
 233
 234         if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
 235                 dev_err(&pdev->dev, "failed to parse the number of vectors\n");
 236                 return -EINVAL;
 237         }
 238
 239         ret = altera_allocate_domains(msi);
 240         if (ret)
 241                 return ret;
 242
 243         msi->irq = platform_get_irq(pdev, 0);
 244         if (msi->irq < 0) {
 245                 ret = msi->irq;
 246                 goto err;
 247         }
 248
 249         irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
 250         platform_set_drvdata(pdev, msi);
 251
 252         return 0;
 253
 254 err:
 255         altera_msi_remove(pdev);
 256         return ret;
 257 }
 258
 259 static const struct of_device_id altera_msi_of_match[] = {
 260         { .compatible = "altr,msi-1.0", NULL },
 261         { },
 262 };
 263
 264 static struct platform_driver altera_msi_driver = {
 265         .driver = {
 266                 .name = "altera-msi",
 267                 .of_match_table = altera_msi_of_match,
 268         },
 269         .probe = altera_msi_probe,
 270         .remove = altera_msi_remove,
 271 };
 272
 273 static int __init altera_msi_init(void)
 274 {
 275         return platform_driver_register(&altera_msi_driver);
 276 }
 277
 278 static void __exit altera_msi_exit(void)
 279 {
 280         platform_driver_unregister(&altera_msi_driver);
 281 }
 282
 283 subsys_initcall(altera_msi_init);
 284 MODULE_DEVICE_TABLE(of, altera_msi_of_match);
 285 module_exit(altera_msi_exit);
 286 MODULE_DESCRIPTION("Altera PCIe MSI support driver");
 287 MODULE_LICENSE("GPL v2");