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Linux/arch/arm/kernel/devtree.c

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  1 /*
  2  *  linux/arch/arm/kernel/devtree.c
  3  *
  4  *  Copyright (C) 2009 Canonical Ltd. <jeremy.kerr@canonical.com>
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License version 2 as
  8  * published by the Free Software Foundation.
  9  */
 10 
 11 #include <linux/init.h>
 12 #include <linux/export.h>
 13 #include <linux/errno.h>
 14 #include <linux/types.h>
 15 #include <linux/bootmem.h>
 16 #include <linux/memblock.h>
 17 #include <linux/of.h>
 18 #include <linux/of_fdt.h>
 19 #include <linux/of_irq.h>
 20 #include <linux/of_platform.h>
 21 #include <linux/smp.h>
 22 
 23 #include <asm/cputype.h>
 24 #include <asm/setup.h>
 25 #include <asm/page.h>
 26 #include <asm/prom.h>
 27 #include <asm/smp_plat.h>
 28 #include <asm/mach/arch.h>
 29 #include <asm/mach-types.h>
 30 
 31 
 32 #ifdef CONFIG_SMP
 33 extern struct of_cpu_method __cpu_method_of_table[];
 34 
 35 static const struct of_cpu_method __cpu_method_of_table_sentinel
 36         __used __section(__cpu_method_of_table_end);
 37 
 38 
 39 static int __init set_smp_ops_by_method(struct device_node *node)
 40 {
 41         const char *method;
 42         struct of_cpu_method *m = __cpu_method_of_table;
 43 
 44         if (of_property_read_string(node, "enable-method", &method))
 45                 return 0;
 46 
 47         for (; m->method; m++)
 48                 if (!strcmp(m->method, method)) {
 49                         smp_set_ops(m->ops);
 50                         return 1;
 51                 }
 52 
 53         return 0;
 54 }
 55 #else
 56 static inline int set_smp_ops_by_method(struct device_node *node)
 57 {
 58         return 1;
 59 }
 60 #endif
 61 
 62 
 63 /*
 64  * arm_dt_init_cpu_maps - Function retrieves cpu nodes from the device tree
 65  * and builds the cpu logical map array containing MPIDR values related to
 66  * logical cpus
 67  *
 68  * Updates the cpu possible mask with the number of parsed cpu nodes
 69  */
 70 void __init arm_dt_init_cpu_maps(void)
 71 {
 72         /*
 73          * Temp logical map is initialized with UINT_MAX values that are
 74          * considered invalid logical map entries since the logical map must
 75          * contain a list of MPIDR[23:0] values where MPIDR[31:24] must
 76          * read as 0.
 77          */
 78         struct device_node *cpu, *cpus;
 79         int found_method = 0;
 80         u32 i, j, cpuidx = 1;
 81         u32 mpidr = is_smp() ? read_cpuid_mpidr() & MPIDR_HWID_BITMASK : 0;
 82 
 83         u32 tmp_map[NR_CPUS] = { [0 ... NR_CPUS-1] = MPIDR_INVALID };
 84         bool bootcpu_valid = false;
 85         cpus = of_find_node_by_path("/cpus");
 86 
 87         if (!cpus)
 88                 return;
 89 
 90         for_each_child_of_node(cpus, cpu) {
 91                 const __be32 *cell;
 92                 int prop_bytes;
 93                 u32 hwid;
 94 
 95                 if (of_node_cmp(cpu->type, "cpu"))
 96                         continue;
 97 
 98                 pr_debug(" * %s...\n", cpu->full_name);
 99                 /*
100                  * A device tree containing CPU nodes with missing "reg"
101                  * properties is considered invalid to build the
102                  * cpu_logical_map.
103                  */
104                 cell = of_get_property(cpu, "reg", &prop_bytes);
105                 if (!cell || prop_bytes < sizeof(*cell)) {
106                         pr_debug(" * %s missing reg property\n",
107                                      cpu->full_name);
108                         of_node_put(cpu);
109                         return;
110                 }
111 
112                 /*
113                  * Bits n:24 must be set to 0 in the DT since the reg property
114                  * defines the MPIDR[23:0].
115                  */
116                 do {
117                         hwid = be32_to_cpu(*cell++);
118                         prop_bytes -= sizeof(*cell);
119                 } while (!hwid && prop_bytes > 0);
120 
121                 if (prop_bytes || (hwid & ~MPIDR_HWID_BITMASK)) {
122                         of_node_put(cpu);
123                         return;
124                 }
125 
126                 /*
127                  * Duplicate MPIDRs are a recipe for disaster.
128                  * Scan all initialized entries and check for
129                  * duplicates. If any is found just bail out.
130                  * temp values were initialized to UINT_MAX
131                  * to avoid matching valid MPIDR[23:0] values.
132                  */
133                 for (j = 0; j < cpuidx; j++)
134                         if (WARN(tmp_map[j] == hwid,
135                                  "Duplicate /cpu reg properties in the DT\n")) {
136                                 of_node_put(cpu);
137                                 return;
138                         }
139 
140                 /*
141                  * Build a stashed array of MPIDR values. Numbering scheme
142                  * requires that if detected the boot CPU must be assigned
143                  * logical id 0. Other CPUs get sequential indexes starting
144                  * from 1. If a CPU node with a reg property matching the
145                  * boot CPU MPIDR is detected, this is recorded so that the
146                  * logical map built from DT is validated and can be used
147                  * to override the map created in smp_setup_processor_id().
148                  */
149                 if (hwid == mpidr) {
150                         i = 0;
151                         bootcpu_valid = true;
152                 } else {
153                         i = cpuidx++;
154                 }
155 
156                 if (WARN(cpuidx > nr_cpu_ids, "DT /cpu %u nodes greater than "
157                                                "max cores %u, capping them\n",
158                                                cpuidx, nr_cpu_ids)) {
159                         cpuidx = nr_cpu_ids;
160                         of_node_put(cpu);
161                         break;
162                 }
163 
164                 tmp_map[i] = hwid;
165 
166                 if (!found_method)
167                         found_method = set_smp_ops_by_method(cpu);
168         }
169 
170         /*
171          * Fallback to an enable-method in the cpus node if nothing found in
172          * a cpu node.
173          */
174         if (!found_method)
175                 set_smp_ops_by_method(cpus);
176 
177         if (!bootcpu_valid) {
178                 pr_warn("DT missing boot CPU MPIDR[23:0], fall back to default cpu_logical_map\n");
179                 return;
180         }
181 
182         /*
183          * Since the boot CPU node contains proper data, and all nodes have
184          * a reg property, the DT CPU list can be considered valid and the
185          * logical map created in smp_setup_processor_id() can be overridden
186          */
187         for (i = 0; i < cpuidx; i++) {
188                 set_cpu_possible(i, true);
189                 cpu_logical_map(i) = tmp_map[i];
190                 pr_debug("cpu logical map 0x%x\n", cpu_logical_map(i));
191         }
192 }
193 
194 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
195 {
196         return phys_id == cpu_logical_map(cpu);
197 }
198 
199 static const void * __init arch_get_next_mach(const char *const **match)
200 {
201         static const struct machine_desc *mdesc = __arch_info_begin;
202         const struct machine_desc *m = mdesc;
203 
204         if (m >= __arch_info_end)
205                 return NULL;
206 
207         mdesc++;
208         *match = m->dt_compat;
209         return m;
210 }
211 
212 /**
213  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
214  * @dt_phys: physical address of dt blob
215  *
216  * If a dtb was passed to the kernel in r2, then use it to choose the
217  * correct machine_desc and to setup the system.
218  */
219 const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
220 {
221         const struct machine_desc *mdesc, *mdesc_best = NULL;
222 
223 #if defined(CONFIG_ARCH_MULTIPLATFORM) || defined(CONFIG_ARM_SINGLE_ARMV7M)
224         DT_MACHINE_START(GENERIC_DT, "Generic DT based system")
225                 .l2c_aux_val = 0x0,
226                 .l2c_aux_mask = ~0x0,
227         MACHINE_END
228 
229         mdesc_best = &__mach_desc_GENERIC_DT;
230 #endif
231 
232         if (!dt_phys || !early_init_dt_verify(phys_to_virt(dt_phys)))
233                 return NULL;
234 
235         mdesc = of_flat_dt_match_machine(mdesc_best, arch_get_next_mach);
236 
237         if (!mdesc) {
238                 const char *prop;
239                 int size;
240                 unsigned long dt_root;
241 
242                 early_print("\nError: unrecognized/unsupported "
243                             "device tree compatible list:\n[ ");
244 
245                 dt_root = of_get_flat_dt_root();
246                 prop = of_get_flat_dt_prop(dt_root, "compatible", &size);
247                 while (size > 0) {
248                         early_print("'%s' ", prop);
249                         size -= strlen(prop) + 1;
250                         prop += strlen(prop) + 1;
251                 }
252                 early_print("]\n\n");
253 
254                 dump_machine_table(); /* does not return */
255         }
256 
257         /* We really don't want to do this, but sometimes firmware provides buggy data */
258         if (mdesc->dt_fixup)
259                 mdesc->dt_fixup();
260 
261         early_init_dt_scan_nodes();
262 
263         /* Change machine number to match the mdesc we're using */
264         __machine_arch_type = mdesc->nr;
265 
266         return mdesc;
267 }
268 

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