1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Coherency fabric (Aurora) support for Armada 370, 375, 38x and XP
4 * platforms.
5 *
6 * Copyright (C) 2012 Marvell
7 *
8 * Yehuda Yitschak <yehuday@marvell.com>
9 * Gregory Clement <gregory.clement@free-electrons.com>
10 * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
11 *
12 * The Armada 370, 375, 38x and XP SOCs have a coherency fabric which is
13 * responsible for ensuring hardware coherency between all CPUs and between
14 * CPUs and I/O masters. This file initializes the coherency fabric and
15 * supplies basic routines for configuring and controlling hardware coherency
16 */
17
18 #define pr_fmt(fmt) "mvebu-coherency: " fmt
19
20 #include <linux/kernel.h>
21 #include <linux/init.h>
22 #include <linux/of_address.h>
23 #include <linux/io.h>
24 #include <linux/smp.h>
25 #include <linux/dma-map-ops.h>
26 #include <linux/platform_device.h>
27 #include <linux/slab.h>
28 #include <linux/mbus.h>
29 #include <linux/pci.h>
30 #include <asm/smp_plat.h>
31 #include <asm/cacheflush.h>
32 #include <asm/mach/map.h>
33 #include <asm/dma-mapping.h>
34 #include "coherency.h"
35 #include "mvebu-soc-id.h"
36
37 unsigned long coherency_phys_base;
38 void __iomem *coherency_base;
39 static void __iomem *coherency_cpu_base;
40 static void __iomem *cpu_config_base;
41
42 /* Coherency fabric registers */
43 #define IO_SYNC_BARRIER_CTL_OFFSET 0x0
44
45 enum {
46 COHERENCY_FABRIC_TYPE_NONE,
47 COHERENCY_FABRIC_TYPE_ARMADA_370_XP,
48 COHERENCY_FABRIC_TYPE_ARMADA_375,
49 COHERENCY_FABRIC_TYPE_ARMADA_380,
50 };
51
52 static const struct of_device_id of_coherency_table[] = {
53 {.compatible = "marvell,coherency-fabric",
54 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_370_XP },
55 {.compatible = "marvell,armada-375-coherency-fabric",
56 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_375 },
57 {.compatible = "marvell,armada-380-coherency-fabric",
58 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_380 },
59 { /* end of list */ },
60 };
61
62 /* Functions defined in coherency_ll.S */
63 int ll_enable_coherency(void);
64 void ll_add_cpu_to_smp_group(void);
65
66 #define CPU_CONFIG_SHARED_L2 BIT(16)
67
68 /*
69 * Disable the "Shared L2 Present" bit in CPU Configuration register
70 * on Armada XP.
71 *
72 * The "Shared L2 Present" bit affects the "level of coherence" value
73 * in the clidr CP15 register. Cache operation functions such as
74 * "flush all" and "invalidate all" operate on all the cache levels
75 * that included in the defined level of coherence. When HW I/O
76 * coherency is used, this bit causes unnecessary flushes of the L2
77 * cache.
78 */
79 static void armada_xp_clear_shared_l2(void)
80 {
81 u32 reg;
82
83 if (!cpu_config_base)
84 return;
85
86 reg = readl(cpu_config_base);
87 reg &= ~CPU_CONFIG_SHARED_L2;
88 writel(reg, cpu_config_base);
89 }
90
91 static int mvebu_hwcc_notifier(struct notifier_block *nb,
92 unsigned long event, void *__dev)
93 {
94 struct device *dev = __dev;
95
96 if (event != BUS_NOTIFY_ADD_DEVICE)
97 return NOTIFY_DONE;
98 dev->dma_coherent = true;
99
100 return NOTIFY_OK;
101 }
102
103 static struct notifier_block mvebu_hwcc_nb = {
104 .notifier_call = mvebu_hwcc_notifier,
105 };
106
107 static struct notifier_block mvebu_hwcc_pci_nb __maybe_unused = {
108 .notifier_call = mvebu_hwcc_notifier,
109 };
110
111 static int armada_xp_clear_l2_starting(unsigned int cpu)
112 {
113 armada_xp_clear_shared_l2();
114 return 0;
115 }
116
117 static void __init armada_370_coherency_init(struct device_node *np)
118 {
119 struct resource res;
120 struct device_node *cpu_config_np;
121
122 of_address_to_resource(np, 0, &res);
123 coherency_phys_base = res.start;
124 /*
125 * Ensure secondary CPUs will see the updated value,
126 * which they read before they join the coherency
127 * fabric, and therefore before they are coherent with
128 * the boot CPU cache.
129 */
130 sync_cache_w(&coherency_phys_base);
131 coherency_base = of_iomap(np, 0);
132 coherency_cpu_base = of_iomap(np, 1);
133
134 cpu_config_np = of_find_compatible_node(NULL, NULL,
135 "marvell,armada-xp-cpu-config");
136 if (!cpu_config_np)
137 goto exit;
138
139 cpu_config_base = of_iomap(cpu_config_np, 0);
140 if (!cpu_config_base) {
141 of_node_put(cpu_config_np);
142 goto exit;
143 }
144
145 of_node_put(cpu_config_np);
146
147 cpuhp_setup_state_nocalls(CPUHP_AP_ARM_MVEBU_COHERENCY,
148 "arm/mvebu/coherency:starting",
149 armada_xp_clear_l2_starting, NULL);
150 exit:
151 set_cpu_coherent();
152 }
153
154 /*
155 * This ioremap hook is used on Armada 375/38x to ensure that all MMIO
156 * areas are mapped as MT_UNCACHED instead of MT_DEVICE. This is
157 * needed for the HW I/O coherency mechanism to work properly without
158 * deadlock.
159 */
160 static void __iomem *
161 armada_wa_ioremap_caller(phys_addr_t phys_addr, size_t size,
162 unsigned int mtype, void *caller)
163 {
164 mtype = MT_UNCACHED;
165 return __arm_ioremap_caller(phys_addr, size, mtype, caller);
166 }
167
168 static void __init armada_375_380_coherency_init(struct device_node *np)
169 {
170 struct device_node *cache_dn;
171
172 coherency_cpu_base = of_iomap(np, 0);
173 arch_ioremap_caller = armada_wa_ioremap_caller;
174 pci_ioremap_set_mem_type(MT_UNCACHED);
175
176 /*
177 * We should switch the PL310 to I/O coherency mode only if
178 * I/O coherency is actually enabled.
179 */
180 if (!coherency_available())
181 return;
182
183 /*
184 * Add the PL310 property "arm,io-coherent". This makes sure the
185 * outer sync operation is not used, which allows to
186 * workaround the system erratum that causes deadlocks when
187 * doing PCIe in an SMP situation on Armada 375 and Armada
188 * 38x.
189 */
190 for_each_compatible_node(cache_dn, NULL, "arm,pl310-cache") {
191 struct property *p;
192
193 p = kzalloc(sizeof(*p), GFP_KERNEL);
194 p->name = kstrdup("arm,io-coherent", GFP_KERNEL);
195 of_add_property(cache_dn, p);
196 }
197 }
198
199 static int coherency_type(void)
200 {
201 struct device_node *np;
202 const struct of_device_id *match;
203 int type;
204
205 /*
206 * The coherency fabric is needed:
207 * - For coherency between processors on Armada XP, so only
208 * when SMP is enabled.
209 * - For coherency between the processor and I/O devices, but
210 * this coherency requires many pre-requisites (write
211 * allocate cache policy, shareable pages, SMP bit set) that
212 * are only meant in SMP situations.
213 *
214 * Note that this means that on Armada 370, there is currently
215 * no way to use hardware I/O coherency, because even when
216 * CONFIG_SMP is enabled, is_smp() returns false due to the
217 * Armada 370 being a single-core processor. To lift this
218 * limitation, we would have to find a way to make the cache
219 * policy set to write-allocate (on all Armada SoCs), and to
220 * set the shareable attribute in page tables (on all Armada
221 * SoCs except the Armada 370). Unfortunately, such decisions
222 * are taken very early in the kernel boot process, at a point
223 * where we don't know yet on which SoC we are running.
224
225 */
226 if (!is_smp())
227 return COHERENCY_FABRIC_TYPE_NONE;
228
229 np = of_find_matching_node_and_match(NULL, of_coherency_table, &match);
230 if (!np)
231 return COHERENCY_FABRIC_TYPE_NONE;
232
233 type = (int) match->data;
234
235 of_node_put(np);
236
237 return type;
238 }
239
240 int set_cpu_coherent(void)
241 {
242 int type = coherency_type();
243
244 if (type == COHERENCY_FABRIC_TYPE_ARMADA_370_XP) {
245 if (!coherency_base) {
246 pr_warn("Can't make current CPU cache coherent.\n");
247 pr_warn("Coherency fabric is not initialized\n");
248 return 1;
249 }
250
251 armada_xp_clear_shared_l2();
252 ll_add_cpu_to_smp_group();
253 return ll_enable_coherency();
254 }
255
256 return 0;
257 }
258
259 int coherency_available(void)
260 {
261 return coherency_type() != COHERENCY_FABRIC_TYPE_NONE;
262 }
263
264 int __init coherency_init(void)
265 {
266 int type = coherency_type();
267 struct device_node *np;
268
269 np = of_find_matching_node(NULL, of_coherency_table);
270
271 if (type == COHERENCY_FABRIC_TYPE_ARMADA_370_XP)
272 armada_370_coherency_init(np);
273 else if (type == COHERENCY_FABRIC_TYPE_ARMADA_375 ||
274 type == COHERENCY_FABRIC_TYPE_ARMADA_380)
275 armada_375_380_coherency_init(np);
276
277 of_node_put(np);
278
279 return 0;
280 }
281
282 static int __init coherency_late_init(void)
283 {
284 if (coherency_available())
285 bus_register_notifier(&platform_bus_type,
286 &mvebu_hwcc_nb);
287 return 0;
288 }
289
290 postcore_initcall(coherency_late_init);
291
292 #if IS_ENABLED(CONFIG_PCI)
293 static int __init coherency_pci_init(void)
294 {
295 if (coherency_available())
296 bus_register_notifier(&pci_bus_type,
297 &mvebu_hwcc_pci_nb);
298 return 0;
299 }
300
301 arch_initcall(coherency_pci_init);
302 #endif
303
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