xref: /linux/arch/arm/mach-mvebu/coherency.c (revision 4f2c0a4acffbec01079c28f839422e64ddeff004)
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  */
armada_xp_clear_shared_l2(void)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 
mvebu_hwcc_notifier(struct notifier_block * nb,unsigned long event,void * __dev)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 
armada_xp_clear_l2_starting(unsigned int cpu)111 static int armada_xp_clear_l2_starting(unsigned int cpu)
112 {
113 	armada_xp_clear_shared_l2();
114 	return 0;
115 }
116 
armada_370_coherency_init(struct device_node * np)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 *
armada_wa_ioremap_caller(phys_addr_t phys_addr,size_t size,unsigned int mtype,void * caller)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 
armada_375_380_coherency_init(struct device_node * np)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 
coherency_type(void)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 
set_cpu_coherent(void)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 
coherency_available(void)259 int coherency_available(void)
260 {
261 	return coherency_type() != COHERENCY_FABRIC_TYPE_NONE;
262 }
263 
coherency_init(void)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 
coherency_late_init(void)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)
coherency_pci_init(void)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