1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/irqchip/chained_irq.h>
  3#include <linux/irqdomain.h>
  4#include <linux/pci-ecam.h>
  5#include <linux/delay.h>
  6#include <linux/msi.h>
  7#include <linux/of_address.h>
  8
  9#define MSI_MAX			256
 10
 11#define SMP8759_MUX		0x48
 12#define SMP8759_TEST_OUT	0x74
 13#define SMP8759_DOORBELL	0x7c
 14#define SMP8759_STATUS		0x80
 15#define SMP8759_ENABLE		0xa0
 16
 17struct tango_pcie {
 18	DECLARE_BITMAP(used_msi, MSI_MAX);
 19	u64			msi_doorbell;
 20	spinlock_t		used_msi_lock;
 21	void __iomem		*base;
 22	struct irq_domain	*dom;
 23};
 24
 25static void tango_msi_isr(struct irq_desc *desc)
 26{
 27	struct irq_chip *chip = irq_desc_get_chip(desc);
 28	struct tango_pcie *pcie = irq_desc_get_handler_data(desc);
 29	unsigned long status, base, virq, idx, pos = 0;
 30
 31	chained_irq_enter(chip, desc);
 32	spin_lock(&pcie->used_msi_lock);
 33
 34	while ((pos = find_next_bit(pcie->used_msi, MSI_MAX, pos)) < MSI_MAX) {
 35		base = round_down(pos, 32);
 36		status = readl_relaxed(pcie->base + SMP8759_STATUS + base / 8);
 37		for_each_set_bit(idx, &status, 32) {
 38			virq = irq_find_mapping(pcie->dom, base + idx);
 39			generic_handle_irq(virq);
 40		}
 41		pos = base + 32;
 42	}
 43
 44	spin_unlock(&pcie->used_msi_lock);
 45	chained_irq_exit(chip, desc);
 46}
 47
 48static void tango_ack(struct irq_data *d)
 49{
 50	struct tango_pcie *pcie = d->chip_data;
 51	u32 offset = (d->hwirq / 32) * 4;
 52	u32 bit = BIT(d->hwirq % 32);
 53
 54	writel_relaxed(bit, pcie->base + SMP8759_STATUS + offset);
 55}
 56
 57static void update_msi_enable(struct irq_data *d, bool unmask)
 58{
 59	unsigned long flags;
 60	struct tango_pcie *pcie = d->chip_data;
 61	u32 offset = (d->hwirq / 32) * 4;
 62	u32 bit = BIT(d->hwirq % 32);
 63	u32 val;
 64
 65	spin_lock_irqsave(&pcie->used_msi_lock, flags);
 66	val = readl_relaxed(pcie->base + SMP8759_ENABLE + offset);
 67	val = unmask ? val | bit : val & ~bit;
 68	writel_relaxed(val, pcie->base + SMP8759_ENABLE + offset);
 69	spin_unlock_irqrestore(&pcie->used_msi_lock, flags);
 70}
 71
 72static void tango_mask(struct irq_data *d)
 73{
 74	update_msi_enable(d, false);
 75}
 76
 77static void tango_unmask(struct irq_data *d)
 78{
 79	update_msi_enable(d, true);
 80}
 81
 82static int tango_set_affinity(struct irq_data *d, const struct cpumask *mask,
 83			      bool force)
 84{
 85	return -EINVAL;
 86}
 87
 88static void tango_compose_msi_msg(struct irq_data *d, struct msi_msg *msg)
 89{
 90	struct tango_pcie *pcie = d->chip_data;
 91	msg->address_lo = lower_32_bits(pcie->msi_doorbell);
 92	msg->address_hi = upper_32_bits(pcie->msi_doorbell);
 93	msg->data = d->hwirq;
 94}
 95
 96static struct irq_chip tango_chip = {
 97	.irq_ack		= tango_ack,
 98	.irq_mask		= tango_mask,
 99	.irq_unmask		= tango_unmask,
100	.irq_set_affinity	= tango_set_affinity,
101	.irq_compose_msi_msg	= tango_compose_msi_msg,
102};
103
104static void msi_ack(struct irq_data *d)
105{
106	irq_chip_ack_parent(d);
107}
108
109static void msi_mask(struct irq_data *d)
110{
111	pci_msi_mask_irq(d);
112	irq_chip_mask_parent(d);
113}
114
115static void msi_unmask(struct irq_data *d)
116{
117	pci_msi_unmask_irq(d);
118	irq_chip_unmask_parent(d);
119}
120
121static struct irq_chip msi_chip = {
122	.name = "MSI",
123	.irq_ack = msi_ack,
124	.irq_mask = msi_mask,
125	.irq_unmask = msi_unmask,
126};
127
128static struct msi_domain_info msi_dom_info = {
129	.flags	= MSI_FLAG_PCI_MSIX
130		| MSI_FLAG_USE_DEF_DOM_OPS
131		| MSI_FLAG_USE_DEF_CHIP_OPS,
132	.chip	= &msi_chip,
133};
134
135static int tango_irq_domain_alloc(struct irq_domain *dom, unsigned int virq,
136				  unsigned int nr_irqs, void *args)
137{
138	struct tango_pcie *pcie = dom->host_data;
139	unsigned long flags;
140	int pos;
141
142	spin_lock_irqsave(&pcie->used_msi_lock, flags);
143	pos = find_first_zero_bit(pcie->used_msi, MSI_MAX);
144	if (pos >= MSI_MAX) {
145		spin_unlock_irqrestore(&pcie->used_msi_lock, flags);
146		return -ENOSPC;
147	}
148	__set_bit(pos, pcie->used_msi);
149	spin_unlock_irqrestore(&pcie->used_msi_lock, flags);
150	irq_domain_set_info(dom, virq, pos, &tango_chip,
151			pcie, handle_edge_irq, NULL, NULL);
152
153	return 0;
154}
155
156static void tango_irq_domain_free(struct irq_domain *dom, unsigned int virq,
157				  unsigned int nr_irqs)
158{
159	unsigned long flags;
160	struct irq_data *d = irq_domain_get_irq_data(dom, virq);
161	struct tango_pcie *pcie = d->chip_data;
162
163	spin_lock_irqsave(&pcie->used_msi_lock, flags);
164	__clear_bit(d->hwirq, pcie->used_msi);
165	spin_unlock_irqrestore(&pcie->used_msi_lock, flags);
166}
167
168static const struct irq_domain_ops dom_ops = {
169	.alloc	= tango_irq_domain_alloc,
170	.free	= tango_irq_domain_free,
171};
172
173static int smp8759_config_read(struct pci_bus *bus, unsigned int devfn,
174			       int where, int size, u32 *val)
175{
176	struct pci_config_window *cfg = bus->sysdata;
177	struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
178	int ret;
179
180	/* Reads in configuration space outside devfn 0 return garbage */
181	if (devfn != 0)
182		return PCIBIOS_FUNC_NOT_SUPPORTED;
183
184	/*
185	 * PCI config and MMIO accesses are muxed.  Linux doesn't have a
186	 * mutual exclusion mechanism for config vs. MMIO accesses, so
187	 * concurrent accesses may cause corruption.
188	 */
189	writel_relaxed(1, pcie->base + SMP8759_MUX);
190	ret = pci_generic_config_read(bus, devfn, where, size, val);
191	writel_relaxed(0, pcie->base + SMP8759_MUX);
192
193	return ret;
194}
195
196static int smp8759_config_write(struct pci_bus *bus, unsigned int devfn,
197				int where, int size, u32 val)
198{
199	struct pci_config_window *cfg = bus->sysdata;
200	struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
201	int ret;
202
203	writel_relaxed(1, pcie->base + SMP8759_MUX);
204	ret = pci_generic_config_write(bus, devfn, where, size, val);
205	writel_relaxed(0, pcie->base + SMP8759_MUX);
206
207	return ret;
208}
209
210static const struct pci_ecam_ops smp8759_ecam_ops = {
211	.bus_shift	= 20,
212	.pci_ops	= {
213		.map_bus	= pci_ecam_map_bus,
214		.read		= smp8759_config_read,
215		.write		= smp8759_config_write,
216	}
217};
218
219static int tango_pcie_link_up(struct tango_pcie *pcie)
220{
221	void __iomem *test_out = pcie->base + SMP8759_TEST_OUT;
222	int i;
223
224	writel_relaxed(16, test_out);
225	for (i = 0; i < 10; ++i) {
226		u32 ltssm_state = readl_relaxed(test_out) >> 8;
227		if ((ltssm_state & 0x1f) == 0xf) /* L0 */
228			return 1;
229		usleep_range(3000, 4000);
230	}
231
232	return 0;
233}
234
235static int tango_pcie_probe(struct platform_device *pdev)
236{
237	struct device *dev = &pdev->dev;
238	struct tango_pcie *pcie;
239	struct resource *res;
240	struct fwnode_handle *fwnode = of_node_to_fwnode(dev->of_node);
241	struct irq_domain *msi_dom, *irq_dom;
242	struct of_pci_range_parser parser;
243	struct of_pci_range range;
244	int virq, offset;
245
246	dev_warn(dev, "simultaneous PCI config and MMIO accesses may cause data corruption\n");
247	add_taint(TAINT_CRAP, LOCKDEP_STILL_OK);
248
249	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
250	if (!pcie)
251		return -ENOMEM;
252
253	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
254	pcie->base = devm_ioremap_resource(dev, res);
255	if (IS_ERR(pcie->base))
256		return PTR_ERR(pcie->base);
257
258	platform_set_drvdata(pdev, pcie);
259
260	if (!tango_pcie_link_up(pcie))
261		return -ENODEV;
262
263	if (of_pci_dma_range_parser_init(&parser, dev->of_node) < 0)
264		return -ENOENT;
265
266	if (of_pci_range_parser_one(&parser, &range) == NULL)
267		return -ENOENT;
268
269	range.pci_addr += range.size;
270	pcie->msi_doorbell = range.pci_addr + res->start + SMP8759_DOORBELL;
271
272	for (offset = 0; offset < MSI_MAX / 8; offset += 4)
273		writel_relaxed(0, pcie->base + SMP8759_ENABLE + offset);
274
275	virq = platform_get_irq(pdev, 1);
276	if (virq < 0)
277		return virq;
278
279	irq_dom = irq_domain_create_linear(fwnode, MSI_MAX, &dom_ops, pcie);
280	if (!irq_dom) {
281		dev_err(dev, "Failed to create IRQ domain\n");
282		return -ENOMEM;
283	}
284
285	msi_dom = pci_msi_create_irq_domain(fwnode, &msi_dom_info, irq_dom);
286	if (!msi_dom) {
287		dev_err(dev, "Failed to create MSI domain\n");
288		irq_domain_remove(irq_dom);
289		return -ENOMEM;
290	}
291
292	pcie->dom = irq_dom;
293	spin_lock_init(&pcie->used_msi_lock);
294	irq_set_chained_handler_and_data(virq, tango_msi_isr, pcie);
295
296	return pci_host_common_probe(pdev);
297}
298
299static const struct of_device_id tango_pcie_ids[] = {
300	{
301		.compatible = "sigma,smp8759-pcie",
302		.data = &smp8759_ecam_ops,
303	},
304	{ },
305};
306
307static struct platform_driver tango_pcie_driver = {
308	.probe	= tango_pcie_probe,
309	.driver	= {
310		.name = KBUILD_MODNAME,
311		.of_match_table = tango_pcie_ids,
312		.suppress_bind_attrs = true,
313	},
314};
315builtin_platform_driver(tango_pcie_driver);
316
317/*
318 * The root complex advertises the wrong device class.
319 * Header Type 1 is for PCI-to-PCI bridges.
320 */
321static void tango_fixup_class(struct pci_dev *dev)
322{
323	dev->class = PCI_CLASS_BRIDGE_PCI << 8;
324}
325DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0024, tango_fixup_class);
326DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0028, tango_fixup_class);
327
328/*
329 * The root complex exposes a "fake" BAR, which is used to filter
330 * bus-to-system accesses.  Only accesses within the range defined by this
331 * BAR are forwarded to the host, others are ignored.
332 *
333 * By default, the DMA framework expects an identity mapping, and DRAM0 is
334 * mapped at 0x80000000.
335 */
336static void tango_fixup_bar(struct pci_dev *dev)
337{
338	dev->non_compliant_bars = true;
339	pci_write_config_dword(dev, PCI_BASE_ADDRESS_0, 0x80000000);
340}
341DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0024, tango_fixup_bar);
342DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0028, tango_fixup_bar);