summaryrefslogtreecommitdiffstats
path: root/arch/arc/kernel/mcip.c
blob: f39142acc89e032627ef88431ac4775e71949ed2 (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
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
/*
 * ARC ARConnect (MultiCore IP) support (formerly known as MCIP)
 *
 * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/smp.h>
#include <linux/irq.h>
#include <linux/spinlock.h>
#include <asm/irqflags-arcv2.h>
#include <asm/mcip.h>
#include <asm/setup.h>

static DEFINE_RAW_SPINLOCK(mcip_lock);

#ifdef CONFIG_SMP

static char smp_cpuinfo_buf[128];

static void mcip_setup_per_cpu(int cpu)
{
	smp_ipi_irq_setup(cpu, IPI_IRQ);
	smp_ipi_irq_setup(cpu, SOFTIRQ_IRQ);
}

static void mcip_ipi_send(int cpu)
{
	unsigned long flags;
	int ipi_was_pending;

	/* ARConnect can only send IPI to others */
	if (unlikely(cpu == raw_smp_processor_id())) {
		arc_softirq_trigger(SOFTIRQ_IRQ);
		return;
	}

	raw_spin_lock_irqsave(&mcip_lock, flags);

	/*
	 * If receiver already has a pending interrupt, elide sending this one.
	 * Linux cross core calling works well with concurrent IPIs
	 * coalesced into one
	 * see arch/arc/kernel/smp.c: ipi_send_msg_one()
	 */
	__mcip_cmd(CMD_INTRPT_READ_STATUS, cpu);
	ipi_was_pending = read_aux_reg(ARC_REG_MCIP_READBACK);
	if (!ipi_was_pending)
		__mcip_cmd(CMD_INTRPT_GENERATE_IRQ, cpu);

	raw_spin_unlock_irqrestore(&mcip_lock, flags);
}

static void mcip_ipi_clear(int irq)
{
	unsigned int cpu, c;
	unsigned long flags;

	if (unlikely(irq == SOFTIRQ_IRQ)) {
		arc_softirq_clear(irq);
		return;
	}

	raw_spin_lock_irqsave(&mcip_lock, flags);

	/* Who sent the IPI */
	__mcip_cmd(CMD_INTRPT_CHECK_SOURCE, 0);

	cpu = read_aux_reg(ARC_REG_MCIP_READBACK);	/* 1,2,4,8... */

	/*
	 * In rare case, multiple concurrent IPIs sent to same target can
	 * possibly be coalesced by MCIP into 1 asserted IRQ, so @cpus can be
	 * "vectored" (multiple bits sets) as opposed to typical single bit
	 */
	do {
		c = __ffs(cpu);			/* 0,1,2,3 */
		__mcip_cmd(CMD_INTRPT_GENERATE_ACK, c);
		cpu &= ~(1U << c);
	} while (cpu);

	raw_spin_unlock_irqrestore(&mcip_lock, flags);
}

static void mcip_probe_n_setup(void)
{
	struct mcip_bcr mp;

	READ_BCR(ARC_REG_MCIP_BCR, mp);

	sprintf(smp_cpuinfo_buf,
		"Extn [SMP]\t: ARConnect (v%d): %d cores with %s%s%s%s%s\n",
		mp.ver, mp.num_cores,
		IS_AVAIL1(mp.ipi, "IPI "),
		IS_AVAIL1(mp.idu, "IDU "),
		IS_AVAIL1(mp.llm, "LLM "),
		IS_AVAIL1(mp.dbg, "DEBUG "),
		IS_AVAIL1(mp.gfrc, "GFRC"));

	cpuinfo_arc700[0].extn.gfrc = mp.gfrc;

	if (mp.dbg) {
		__mcip_cmd_data(CMD_DEBUG_SET_SELECT, 0, 0xf);
		__mcip_cmd_data(CMD_DEBUG_SET_MASK, 0xf, 0xf);
	}
}

struct plat_smp_ops plat_smp_ops = {
	.info		= smp_cpuinfo_buf,
	.init_early_smp	= mcip_probe_n_setup,
	.init_per_cpu	= mcip_setup_per_cpu,
	.ipi_send	= mcip_ipi_send,
	.ipi_clear	= mcip_ipi_clear,
};

#endif

/***************************************************************************
 * ARCv2 Interrupt Distribution Unit (IDU)
 *
 * Connects external "COMMON" IRQs to core intc, providing:
 *  -dynamic routing (IRQ affinity)
 *  -load balancing (Round Robin interrupt distribution)
 *  -1:N distribution
 *
 * It physically resides in the MCIP hw block
 */

#include <linux/irqchip.h>
#include <linux/of.h>
#include <linux/of_irq.h>

/*
 * Set the DEST for @cmn_irq to @cpu_mask (1 bit per core)
 */
static void idu_set_dest(unsigned int cmn_irq, unsigned int cpu_mask)
{
	__mcip_cmd_data(CMD_IDU_SET_DEST, cmn_irq, cpu_mask);
}

static void idu_set_mode(unsigned int cmn_irq, unsigned int lvl,
			   unsigned int distr)
{
	union {
		unsigned int word;
		struct {
			unsigned int distr:2, pad:2, lvl:1, pad2:27;
		};
	} data;

	data.distr = distr;
	data.lvl = lvl;
	__mcip_cmd_data(CMD_IDU_SET_MODE, cmn_irq, data.word);
}

static void idu_irq_mask(struct irq_data *data)
{
	unsigned long flags;

	raw_spin_lock_irqsave(&mcip_lock, flags);
	__mcip_cmd_data(CMD_IDU_SET_MASK, data->hwirq, 1);
	raw_spin_unlock_irqrestore(&mcip_lock, flags);
}

static void idu_irq_unmask(struct irq_data *data)
{
	unsigned long flags;

	raw_spin_lock_irqsave(&mcip_lock, flags);
	__mcip_cmd_data(CMD_IDU_SET_MASK, data->hwirq, 0);
	raw_spin_unlock_irqrestore(&mcip_lock, flags);
}

#ifdef CONFIG_SMP
static int
idu_irq_set_affinity(struct irq_data *data, const struct cpumask *cpumask,
		     bool force)
{
	unsigned long flags;
	cpumask_t online;
	unsigned int destination_bits;
	unsigned int distribution_mode;

	/* errout if no online cpu per @cpumask */
	if (!cpumask_and(&online, cpumask, cpu_online_mask))
		return -EINVAL;

	raw_spin_lock_irqsave(&mcip_lock, flags);

	destination_bits = cpumask_bits(&online)[0];
	idu_set_dest(data->hwirq, destination_bits);

	if (ffs(destination_bits) == fls(destination_bits))
		distribution_mode = IDU_M_DISTRI_DEST;
	else
		distribution_mode = IDU_M_DISTRI_RR;

	idu_set_mode(data->hwirq, IDU_M_TRIG_LEVEL, distribution_mode);

	raw_spin_unlock_irqrestore(&mcip_lock, flags);

	return IRQ_SET_MASK_OK;
}
#endif

static struct irq_chip idu_irq_chip = {
	.name			= "MCIP IDU Intc",
	.irq_mask		= idu_irq_mask,
	.irq_unmask		= idu_irq_unmask,
#ifdef CONFIG_SMP
	.irq_set_affinity       = idu_irq_set_affinity,
#endif

};

static irq_hw_number_t idu_first_hwirq;

static void idu_cascade_isr(struct irq_desc *desc)
{
	struct irq_domain *idu_domain = irq_desc_get_handler_data(desc);
	irq_hw_number_t core_hwirq = irqd_to_hwirq(irq_desc_get_irq_data(desc));
	irq_hw_number_t idu_hwirq = core_hwirq - idu_first_hwirq;

	generic_handle_irq(irq_find_mapping(idu_domain, idu_hwirq));
}

static int idu_irq_map(struct irq_domain *d, unsigned int virq, irq_hw_number_t hwirq)
{
	irq_set_chip_and_handler(virq, &idu_irq_chip, handle_level_irq);
	irq_set_status_flags(virq, IRQ_MOVE_PCNTXT);

	return 0;
}

static int idu_irq_xlate(struct irq_domain *d, struct device_node *n,
			 const u32 *intspec, unsigned int intsize,
			 irq_hw_number_t *out_hwirq, unsigned int *out_type)
{
	irq_hw_number_t hwirq = *out_hwirq = intspec[0];
	int distri = intspec[1];
	unsigned long flags;

	*out_type = IRQ_TYPE_NONE;

	/* XXX: validate distribution scheme again online cpu mask */
	if (distri == 0) {
		/* 0 - Round Robin to all cpus, otherwise 1 bit per core */
		raw_spin_lock_irqsave(&mcip_lock, flags);
		idu_set_dest(hwirq, BIT(num_online_cpus()) - 1);
		idu_set_mode(hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_RR);
		raw_spin_unlock_irqrestore(&mcip_lock, flags);
	} else {
		/*
		 * DEST based distribution for Level Triggered intr can only
		 * have 1 CPU, so generalize it to always contain 1 cpu
		 */
		int cpu = ffs(distri);

		if (cpu != fls(distri))
			pr_warn("IDU irq %lx distri mode set to cpu %x\n",
				hwirq, cpu);

		raw_spin_lock_irqsave(&mcip_lock, flags);
		idu_set_dest(hwirq, cpu);
		idu_set_mode(hwirq, IDU_M_TRIG_LEVEL, IDU_M_DISTRI_DEST);
		raw_spin_unlock_irqrestore(&mcip_lock, flags);
	}

	return 0;
}

static const struct irq_domain_ops idu_irq_ops = {
	.xlate	= idu_irq_xlate,
	.map	= idu_irq_map,
};

/*
 * [16, 23]: Statically assigned always private-per-core (Timers, WDT, IPI)
 * [24, 23+C]: If C > 0 then "C" common IRQs
 * [24+C, N]: Not statically assigned, private-per-core
 */


static int __init
idu_of_init(struct device_node *intc, struct device_node *parent)
{
	struct irq_domain *domain;
	/* Read IDU BCR to confirm nr_irqs */
	int nr_irqs = of_irq_count(intc);
	int i, virq;
	struct mcip_bcr mp;

	READ_BCR(ARC_REG_MCIP_BCR, mp);

	if (!mp.idu)
		panic("IDU not detected, but DeviceTree using it");

	pr_info("MCIP: IDU referenced from Devicetree %d irqs\n", nr_irqs);

	domain = irq_domain_add_linear(intc, nr_irqs, &idu_irq_ops, NULL);

	/* Parent interrupts (core-intc) are already mapped */

	for (i = 0; i < nr_irqs; i++) {
		/*
		 * Return parent uplink IRQs (towards core intc) 24,25,.....
		 * this step has been done before already
		 * however we need it to get the parent virq and set IDU handler
		 * as first level isr
		 */
		virq = irq_of_parse_and_map(intc, i);
		if (!i)
			idu_first_hwirq = irqd_to_hwirq(irq_get_irq_data(virq));

		irq_set_chained_handler_and_data(virq, idu_cascade_isr, domain);
	}

	__mcip_cmd(CMD_IDU_ENABLE, 0);

	return 0;
}
IRQCHIP_DECLARE(arcv2_idu_intc, "snps,archs-idu-intc", idu_of_init);