summaryrefslogtreecommitdiffstats
path: root/drivers/pci/host/pcie-tango.c
blob: 95049de4131cc46dc7e59e1c6b5dd2020b34f567 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
// SPDX-License-Identifier: GPL-2.0
#include <linux/pci-ecam.h>
#include <linux/delay.h>
#include <linux/of.h>

#define SMP8759_MUX		0x48
#define SMP8759_TEST_OUT	0x74

struct tango_pcie {
	void __iomem *base;
};

static int smp8759_config_read(struct pci_bus *bus, unsigned int devfn,
			       int where, int size, u32 *val)
{
	struct pci_config_window *cfg = bus->sysdata;
	struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
	int ret;

	/* Reads in configuration space outside devfn 0 return garbage */
	if (devfn != 0)
		return PCIBIOS_FUNC_NOT_SUPPORTED;

	/*
	 * PCI config and MMIO accesses are muxed.  Linux doesn't have a
	 * mutual exclusion mechanism for config vs. MMIO accesses, so
	 * concurrent accesses may cause corruption.
	 */
	writel_relaxed(1, pcie->base + SMP8759_MUX);
	ret = pci_generic_config_read(bus, devfn, where, size, val);
	writel_relaxed(0, pcie->base + SMP8759_MUX);

	return ret;
}

static int smp8759_config_write(struct pci_bus *bus, unsigned int devfn,
				int where, int size, u32 val)
{
	struct pci_config_window *cfg = bus->sysdata;
	struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
	int ret;

	writel_relaxed(1, pcie->base + SMP8759_MUX);
	ret = pci_generic_config_write(bus, devfn, where, size, val);
	writel_relaxed(0, pcie->base + SMP8759_MUX);

	return ret;
}

static struct pci_ecam_ops smp8759_ecam_ops = {
	.bus_shift	= 20,
	.pci_ops	= {
		.map_bus	= pci_ecam_map_bus,
		.read		= smp8759_config_read,
		.write		= smp8759_config_write,
	}
};

static int tango_pcie_link_up(struct tango_pcie *pcie)
{
	void __iomem *test_out = pcie->base + SMP8759_TEST_OUT;
	int i;

	writel_relaxed(16, test_out);
	for (i = 0; i < 10; ++i) {
		u32 ltssm_state = readl_relaxed(test_out) >> 8;
		if ((ltssm_state & 0x1f) == 0xf) /* L0 */
			return 1;
		usleep_range(3000, 4000);
	}

	return 0;
}

static int tango_pcie_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct tango_pcie *pcie;
	struct resource *res;
	int ret;

	dev_warn(dev, "simultaneous PCI config and MMIO accesses may cause data corruption\n");
	add_taint(TAINT_CRAP, LOCKDEP_STILL_OK);

	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
	if (!pcie)
		return -ENOMEM;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
	pcie->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(pcie->base))
		return PTR_ERR(pcie->base);

	platform_set_drvdata(pdev, pcie);

	if (!tango_pcie_link_up(pcie))
		return -ENODEV;

	return pci_host_common_probe(pdev, &smp8759_ecam_ops);
}

static const struct of_device_id tango_pcie_ids[] = {
	{ .compatible = "sigma,smp8759-pcie" },
	{ },
};

static struct platform_driver tango_pcie_driver = {
	.probe	= tango_pcie_probe,
	.driver	= {
		.name = KBUILD_MODNAME,
		.of_match_table = tango_pcie_ids,
		.suppress_bind_attrs = true,
	},
};
builtin_platform_driver(tango_pcie_driver);

/*
 * The root complex advertises the wrong device class.
 * Header Type 1 is for PCI-to-PCI bridges.
 */
static void tango_fixup_class(struct pci_dev *dev)
{
	dev->class = PCI_CLASS_BRIDGE_PCI << 8;
}
DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0024, tango_fixup_class);
DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0028, tango_fixup_class);

/*
 * The root complex exposes a "fake" BAR, which is used to filter
 * bus-to-system accesses.  Only accesses within the range defined by this
 * BAR are forwarded to the host, others are ignored.
 *
 * By default, the DMA framework expects an identity mapping, and DRAM0 is
 * mapped at 0x80000000.
 */
static void tango_fixup_bar(struct pci_dev *dev)
{
	dev->non_compliant_bars = true;
	pci_write_config_dword(dev, PCI_BASE_ADDRESS_0, 0x80000000);
}
DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0024, tango_fixup_bar);
DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0028, tango_fixup_bar);