1/*
  2 * Coherency fabric (Aurora) support for Armada 370, 375, 38x and XP
  3 * platforms.
  4 *
  5 * Copyright (C) 2012 Marvell
  6 *
  7 * Yehuda Yitschak <yehuday@marvell.com>
  8 * Gregory Clement <gregory.clement@free-electrons.com>
  9 * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
 10 *
 11 * This file is licensed under the terms of the GNU General Public
 12 * License version 2.  This program is licensed "as is" without any
 13 * warranty of any kind, whether express or implied.
 14 *
 15 * The Armada 370, 375, 38x and XP SOCs have a coherency fabric which is
 16 * responsible for ensuring hardware coherency between all CPUs and between
 17 * CPUs and I/O masters. This file initializes the coherency fabric and
 18 * supplies basic routines for configuring and controlling hardware coherency
 19 */
 20
 21#define pr_fmt(fmt) "mvebu-coherency: " fmt
 22
 23#include <linux/kernel.h>
 24#include <linux/init.h>
 25#include <linux/of_address.h>
 26#include <linux/io.h>
 27#include <linux/smp.h>
 28#include <linux/dma-mapping.h>
 29#include <linux/platform_device.h>
 30#include <linux/slab.h>
 31#include <linux/mbus.h>
 32#include <linux/pci.h>
 33#include <asm/smp_plat.h>
 34#include <asm/cacheflush.h>
 35#include <asm/mach/map.h>
 36#include <asm/dma-mapping.h>
 37#include "coherency.h"
 38#include "mvebu-soc-id.h"
 39
 40unsigned long coherency_phys_base;
 41void __iomem *coherency_base;
 42static void __iomem *coherency_cpu_base;
 43static void __iomem *cpu_config_base;
 44
 45/* Coherency fabric registers */
 46#define IO_SYNC_BARRIER_CTL_OFFSET		   0x0
 47
 48enum {
 49	COHERENCY_FABRIC_TYPE_NONE,
 50	COHERENCY_FABRIC_TYPE_ARMADA_370_XP,
 51	COHERENCY_FABRIC_TYPE_ARMADA_375,
 52	COHERENCY_FABRIC_TYPE_ARMADA_380,
 53};
 54
 55static const struct of_device_id of_coherency_table[] = {
 56	{.compatible = "marvell,coherency-fabric",
 57	 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_370_XP },
 58	{.compatible = "marvell,armada-375-coherency-fabric",
 59	 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_375 },
 60	{.compatible = "marvell,armada-380-coherency-fabric",
 61	 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_380 },
 62	{ /* end of list */ },
 63};
 64
 65/* Functions defined in coherency_ll.S */
 66int ll_enable_coherency(void);
 67void ll_add_cpu_to_smp_group(void);
 68
 69#define CPU_CONFIG_SHARED_L2 BIT(16)
 70
 71/*
 72 * Disable the "Shared L2 Present" bit in CPU Configuration register
 73 * on Armada XP.
 74 *
 75 * The "Shared L2 Present" bit affects the "level of coherence" value
 76 * in the clidr CP15 register.  Cache operation functions such as
 77 * "flush all" and "invalidate all" operate on all the cache levels
 78 * that included in the defined level of coherence. When HW I/O
 79 * coherency is used, this bit causes unnecessary flushes of the L2
 80 * cache.
 81 */
 82static void armada_xp_clear_shared_l2(void)
 83{
 84	u32 reg;
 85
 86	if (!cpu_config_base)
 87		return;
 88
 89	reg = readl(cpu_config_base);
 90	reg &= ~CPU_CONFIG_SHARED_L2;
 91	writel(reg, cpu_config_base);
 92}
 93
 94static int mvebu_hwcc_notifier(struct notifier_block *nb,
 95			       unsigned long event, void *__dev)
 96{
 97	struct device *dev = __dev;
 98
 99	if (event != BUS_NOTIFY_ADD_DEVICE)
100		return NOTIFY_DONE;
101	set_dma_ops(dev, &arm_coherent_dma_ops);
102
103	return NOTIFY_OK;
104}
105
106static struct notifier_block mvebu_hwcc_nb = {
107	.notifier_call = mvebu_hwcc_notifier,
108};
109
110static struct notifier_block mvebu_hwcc_pci_nb __maybe_unused = {
111	.notifier_call = mvebu_hwcc_notifier,
112};
113
114static int armada_xp_clear_l2_starting(unsigned int cpu)
115{
116	armada_xp_clear_shared_l2();
117	return 0;
118}
119
120static void __init armada_370_coherency_init(struct device_node *np)
121{
122	struct resource res;
123	struct device_node *cpu_config_np;
124
125	of_address_to_resource(np, 0, &res);
126	coherency_phys_base = res.start;
127	/*
128	 * Ensure secondary CPUs will see the updated value,
129	 * which they read before they join the coherency
130	 * fabric, and therefore before they are coherent with
131	 * the boot CPU cache.
132	 */
133	sync_cache_w(&coherency_phys_base);
134	coherency_base = of_iomap(np, 0);
135	coherency_cpu_base = of_iomap(np, 1);
136
137	cpu_config_np = of_find_compatible_node(NULL, NULL,
138						"marvell,armada-xp-cpu-config");
139	if (!cpu_config_np)
140		goto exit;
141
142	cpu_config_base = of_iomap(cpu_config_np, 0);
143	if (!cpu_config_base) {
144		of_node_put(cpu_config_np);
145		goto exit;
146	}
147
148	of_node_put(cpu_config_np);
149
150	cpuhp_setup_state_nocalls(CPUHP_AP_ARM_MVEBU_COHERENCY,
151				  "arm/mvebu/coherency:starting",
152				  armada_xp_clear_l2_starting, NULL);
153exit:
154	set_cpu_coherent();
155}
156
157/*
158 * This ioremap hook is used on Armada 375/38x to ensure that all MMIO
159 * areas are mapped as MT_UNCACHED instead of MT_DEVICE. This is
160 * needed for the HW I/O coherency mechanism to work properly without
161 * deadlock.
162 */
163static void __iomem *
164armada_wa_ioremap_caller(phys_addr_t phys_addr, size_t size,
165			 unsigned int mtype, void *caller)
166{
167	mtype = MT_UNCACHED;
168	return __arm_ioremap_caller(phys_addr, size, mtype, caller);
169}
170
171static void __init armada_375_380_coherency_init(struct device_node *np)
172{
173	struct device_node *cache_dn;
174
175	coherency_cpu_base = of_iomap(np, 0);
176	arch_ioremap_caller = armada_wa_ioremap_caller;
177	pci_ioremap_set_mem_type(MT_UNCACHED);
178
179	/*
180	 * We should switch the PL310 to I/O coherency mode only if
181	 * I/O coherency is actually enabled.
182	 */
183	if (!coherency_available())
184		return;
185
186	/*
187	 * Add the PL310 property "arm,io-coherent". This makes sure the
188	 * outer sync operation is not used, which allows to
189	 * workaround the system erratum that causes deadlocks when
190	 * doing PCIe in an SMP situation on Armada 375 and Armada
191	 * 38x.
192	 */
193	for_each_compatible_node(cache_dn, NULL, "arm,pl310-cache") {
194		struct property *p;
195
196		p = kzalloc(sizeof(*p), GFP_KERNEL);
197		p->name = kstrdup("arm,io-coherent", GFP_KERNEL);
198		of_add_property(cache_dn, p);
199	}
200}
201
202static int coherency_type(void)
203{
204	struct device_node *np;
205	const struct of_device_id *match;
206	int type;
207
208	/*
209	 * The coherency fabric is needed:
210	 * - For coherency between processors on Armada XP, so only
211	 *   when SMP is enabled.
212	 * - For coherency between the processor and I/O devices, but
213	 *   this coherency requires many pre-requisites (write
214	 *   allocate cache policy, shareable pages, SMP bit set) that
215	 *   are only meant in SMP situations.
216	 *
217	 * Note that this means that on Armada 370, there is currently
218	 * no way to use hardware I/O coherency, because even when
219	 * CONFIG_SMP is enabled, is_smp() returns false due to the
220	 * Armada 370 being a single-core processor. To lift this
221	 * limitation, we would have to find a way to make the cache
222	 * policy set to write-allocate (on all Armada SoCs), and to
223	 * set the shareable attribute in page tables (on all Armada
224	 * SoCs except the Armada 370). Unfortunately, such decisions
225	 * are taken very early in the kernel boot process, at a point
226	 * where we don't know yet on which SoC we are running.
227
228	 */
229	if (!is_smp())
230		return COHERENCY_FABRIC_TYPE_NONE;
231
232	np = of_find_matching_node_and_match(NULL, of_coherency_table, &match);
233	if (!np)
234		return COHERENCY_FABRIC_TYPE_NONE;
235
236	type = (int) match->data;
237
238	of_node_put(np);
239
240	return type;
241}
242
243int set_cpu_coherent(void)
244{
245	int type = coherency_type();
246
247	if (type == COHERENCY_FABRIC_TYPE_ARMADA_370_XP) {
248		if (!coherency_base) {
249			pr_warn("Can't make current CPU cache coherent.\n");
250			pr_warn("Coherency fabric is not initialized\n");
251			return 1;
252		}
253
254		armada_xp_clear_shared_l2();
255		ll_add_cpu_to_smp_group();
256		return ll_enable_coherency();
257	}
258
259	return 0;
260}
261
262int coherency_available(void)
263{
264	return coherency_type() != COHERENCY_FABRIC_TYPE_NONE;
265}
266
267int __init coherency_init(void)
268{
269	int type = coherency_type();
270	struct device_node *np;
271
272	np = of_find_matching_node(NULL, of_coherency_table);
273
274	if (type == COHERENCY_FABRIC_TYPE_ARMADA_370_XP)
275		armada_370_coherency_init(np);
276	else if (type == COHERENCY_FABRIC_TYPE_ARMADA_375 ||
277		 type == COHERENCY_FABRIC_TYPE_ARMADA_380)
278		armada_375_380_coherency_init(np);
279
280	of_node_put(np);
281
282	return 0;
283}
284
285static int __init coherency_late_init(void)
286{
287	if (coherency_available())
288		bus_register_notifier(&platform_bus_type,
289				      &mvebu_hwcc_nb);
290	return 0;
291}
292
293postcore_initcall(coherency_late_init);
294
295#if IS_ENABLED(CONFIG_PCI)
296static int __init coherency_pci_init(void)
297{
298	if (coherency_available())
299		bus_register_notifier(&pci_bus_type,
300				       &mvebu_hwcc_pci_nb);
301	return 0;
302}
303
304arch_initcall(coherency_pci_init);
305#endif