C6X: early boot code

Original port to early 2.6 kernel using TI COFF toolchain.
Brought up to date by Mark Salter <[e-mail]>

This patch provides the early boot code for C6X architecture. There is a
16 entry vector table which is used to direct reset and interrupt events. The
vector table entries contain a small amount of code (maximum of 8 opcodes)
which simply branches to the actual event handling code.

The head.S code simply clears BSS, setups up a few control registers, and calls
machine_init followed by start_kernel. The machine_init code in setup.c does
the early flat tree parsing (memory, commandline, etc). At setup_arch time, the
code does the usual memory setup and minimally scans the devicetree for any
needed information.

Signed-off-by: Aurelien Jacquiot <[e-mail]>
Signed-off-by: Mark Salter <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>

arch/c6x/kernel/head.S

···
+;
+;  Port on Texas Instruments TMS320C6x architecture
+;
+;  Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
+;  Author: Aurelien Jacquiot ([e-mail])
+;
+;  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/linkage.h>
+#include <linux/of_fdt.h>
+#include <asm/asm-offsets.h>
+
+	__HEAD
+ENTRY(_c_int00)
+	;; Save magic and pointer
+	MV	.S1	A4,A10
+	MV	.S2	B4,B10
+	MVKL	.S2	__bss_start,B5
+	MVKH	.S2	__bss_start,B5
+	MVKL	.S2	__bss_stop,B6
+	MVKH	.S2	__bss_stop,B6
+	SUB	.L2	B6,B5,B6 ; bss size
+
+	;; Set the stack pointer
+	MVKL	.S2	current_ksp,B0
+	MVKH	.S2	current_ksp,B0
+	LDW	.D2T2	*B0,B15
+
+	;; clear bss
+	SHR	.S2	B6,3,B0	  ; number of dwords to clear
+	ZERO	.L2	B13
+	ZERO	.L2	B12
+bss_loop:
+	BDEC	.S2	bss_loop,B0
+	NOP	3
+	CMPLT	.L2	B0,0,B1
+ [!B1]	STDW	.D2T2	B13:B12,*B5++[1]
+
+	NOP	4
+	AND	.D2	~7,B15,B15
+
+	;; Clear GIE and PGIE
+	MVC	.S2	CSR,B2
+	CLR	.S2	B2,0,1,B2
+	MVC	.S2	B2,CSR
+	MVC	.S2	TSR,B2
+	CLR	.S2	B2,0,1,B2
+	MVC	.S2	B2,TSR
+	MVC	.S2	ITSR,B2
+	CLR	.S2	B2,0,1,B2
+	MVC	.S2	B2,ITSR
+	MVC	.S2	NTSR,B2
+	CLR	.S2	B2,0,1,B2
+	MVC	.S2	B2,NTSR
+
+	;; pass DTB pointer to machine_init (or zero if none)
+	MVKL	.S1	OF_DT_HEADER,A0
+	MVKH	.S1	OF_DT_HEADER,A0
+	CMPEQ	.L1	A10,A0,A0
+  [A0]	MV	.S1X	B10,A4
+  [!A0] MVK	.S1	0,A4
+
+#ifdef CONFIG_C6X_BIG_KERNEL
+	MVKL	.S1	machine_init,A0
+	MVKH	.S1	machine_init,A0
+	B	.S2X	A0
+	ADDKPC  .S2     0f,B3,4
+0:
+#else
+	CALLP	.S2	machine_init,B3
+#endif
+
+	;; Jump to Linux init
+#ifdef CONFIG_C6X_BIG_KERNEL
+	MVKL	.S1	start_kernel,A0
+	MVKH	.S1	start_kernel,A0
+	B	.S2X	A0
+#else
+	B	.S2	start_kernel
+#endif
+	NOP	5
+L1:	BNOP	.S2	L1,5

arch/c6x/kernel/setup.c

···
+/*
+ *  Port on Texas Instruments TMS320C6x architecture
+ *
+ *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
+ *  Author: Aurelien Jacquiot ([e-mail])
+ *
+ *  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/dma-mapping.h>
+#include <linux/memblock.h>
+#include <linux/seq_file.h>
+#include <linux/bootmem.h>
+#include <linux/clkdev.h>
+#include <linux/initrd.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_fdt.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/cache.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/clk.h>
+#include <linux/fs.h>
+#include <linux/of.h>
+
+
+#include <asm/sections.h>
+#include <asm/div64.h>
+#include <asm/setup.h>
+#include <asm/dscr.h>
+#include <asm/clock.h>
+#include <asm/soc.h>
+
+static const char *c6x_soc_name;
+
+int c6x_num_cores;
+EXPORT_SYMBOL_GPL(c6x_num_cores);
+
+unsigned int c6x_silicon_rev;
+EXPORT_SYMBOL_GPL(c6x_silicon_rev);
+
+/*
+ * Device status register. This holds information
+ * about device configuration needed by some drivers.
+ */
+unsigned int c6x_devstat;
+EXPORT_SYMBOL_GPL(c6x_devstat);
+
+/*
+ * Some SoCs have fuse registers holding a unique MAC
+ * address. This is parsed out of the device tree with
+ * the resulting MAC being held here.
+ */
+unsigned char c6x_fuse_mac[6];
+
+unsigned long memory_start;
+unsigned long memory_end;
+
+unsigned long ram_start;
+unsigned long ram_end;
+
+/* Uncached memory for DMA consistent use (memdma=) */
+static unsigned long dma_start __initdata;
+static unsigned long dma_size __initdata;
+
+char c6x_command_line[COMMAND_LINE_SIZE];
+
+#if defined(CONFIG_CMDLINE_BOOL)
+static const char default_command_line[COMMAND_LINE_SIZE] __section(.cmdline) =
+	CONFIG_CMDLINE;
+#endif
+
+struct cpuinfo_c6x {
+	const char *cpu_name;
+	const char *cpu_voltage;
+	const char *mmu;
+	const char *fpu;
+	char *cpu_rev;
+	unsigned int core_id;
+	char __cpu_rev[5];
+};
+
+static DEFINE_PER_CPU(struct cpuinfo_c6x, cpu_data);
+
+unsigned int ticks_per_ns_scaled;
+EXPORT_SYMBOL(ticks_per_ns_scaled);
+
+unsigned int c6x_core_freq;
+
+static void __init get_cpuinfo(void)
+{
+	unsigned cpu_id, rev_id, csr;
+	struct clk *coreclk = clk_get_sys(NULL, "core");
+	unsigned long core_khz;
+	u64 tmp;
+	struct cpuinfo_c6x *p;
+	struct device_node *node, *np;
+
+	p = &per_cpu(cpu_data, smp_processor_id());
+
+	if (!IS_ERR(coreclk))
+		c6x_core_freq = clk_get_rate(coreclk);
+	else {
+		printk(KERN_WARNING
+		       "Cannot find core clock frequency. Using 700MHz\n");
+		c6x_core_freq = 700000000;
+	}
+
+	core_khz = c6x_core_freq / 1000;
+
+	tmp = (uint64_t)core_khz << C6X_NDELAY_SCALE;
+	do_div(tmp, 1000000);
+	ticks_per_ns_scaled = tmp;
+
+	csr = get_creg(CSR);
+	cpu_id = csr >> 24;
+	rev_id = (csr >> 16) & 0xff;
+
+	p->mmu = "none";
+	p->fpu = "none";
+	p->cpu_voltage = "unknown";
+
+	switch (cpu_id) {
+	case 0:
+		p->cpu_name = "C67x";
+		p->fpu = "yes";
+		break;
+	case 2:
+		p->cpu_name = "C62x";
+		break;
+	case 8:
+		p->cpu_name = "C64x";
+		break;
+	case 12:
+		p->cpu_name = "C64x";
+		break;
+	case 16:
+		p->cpu_name = "C64x+";
+		p->cpu_voltage = "1.2";
+		break;
+	default:
+		p->cpu_name = "unknown";
+		break;
+	}
+
+	if (cpu_id < 16) {
+		switch (rev_id) {
+		case 0x1:
+			if (cpu_id > 8) {
+				p->cpu_rev = "DM640/DM641/DM642/DM643";
+				p->cpu_voltage = "1.2 - 1.4";
+			} else {
+				p->cpu_rev = "C6201";
+				p->cpu_voltage = "2.5";
+			}
+			break;
+		case 0x2:
+			p->cpu_rev = "C6201B/C6202/C6211";
+			p->cpu_voltage = "1.8";
+			break;
+		case 0x3:
+			p->cpu_rev = "C6202B/C6203/C6204/C6205";
+			p->cpu_voltage = "1.5";
+			break;
+		case 0x201:
+			p->cpu_rev = "C6701 revision 0 (early CPU)";
+			p->cpu_voltage = "1.8";
+			break;
+		case 0x202:
+			p->cpu_rev = "C6701/C6711/C6712";
+			p->cpu_voltage = "1.8";
+			break;
+		case 0x801:
+			p->cpu_rev = "C64x";
+			p->cpu_voltage = "1.5";
+			break;
+		default:
+			p->cpu_rev = "unknown";
+		}
+	} else {
+		p->cpu_rev = p->__cpu_rev;
+		snprintf(p->__cpu_rev, sizeof(p->__cpu_rev), "0x%x", cpu_id);
+	}
+
+	p->core_id = get_coreid();
+
+	node = of_find_node_by_name(NULL, "cpus");
+	if (node) {
+		for_each_child_of_node(node, np)
+			if (!strcmp("cpu", np->name))
+				++c6x_num_cores;
+		of_node_put(node);
+	}
+
+	node = of_find_node_by_name(NULL, "soc");
+	if (node) {
+		if (of_property_read_string(node, "model", &c6x_soc_name))
+			c6x_soc_name = "unknown";
+		of_node_put(node);
+	} else
+		c6x_soc_name = "unknown";
+
+	printk(KERN_INFO "CPU%d: %s rev %s, %s volts, %uMHz\n",
+	       p->core_id, p->cpu_name, p->cpu_rev,
+	       p->cpu_voltage, c6x_core_freq / 1000000);
+}
+
+/*
+ * Early parsing of the command line
+ */
+static u32 mem_size __initdata;
+
+/* "mem=" parsing. */
+static int __init early_mem(char *p)
+{
+	if (!p)
+		return -EINVAL;
+
+	mem_size = memparse(p, &p);
+	/* don't remove all of memory when handling "mem={invalid}" */
+	if (mem_size == 0)
+		return -EINVAL;
+
+	return 0;
+}
+early_param("mem", early_mem);
+
+/* "memdma=<size>[@<address>]" parsing. */
+static int __init early_memdma(char *p)
+{
+	if (!p)
+		return -EINVAL;
+
+	dma_size = memparse(p, &p);
+	if (*p == '@')
+		dma_start = memparse(p, &p);
+
+	return 0;
+}
+early_param("memdma", early_memdma);
+
+int __init c6x_add_memory(phys_addr_t start, unsigned long size)
+{
+	static int ram_found __initdata;
+
+	/* We only handle one bank (the one with PAGE_OFFSET) for now */
+	if (ram_found)
+		return -EINVAL;
+
+	if (start > PAGE_OFFSET || PAGE_OFFSET >= (start + size))
+		return 0;
+
+	ram_start = start;
+	ram_end = start + size;
+
+	ram_found = 1;
+	return 0;
+}
+
+/*
+ * Do early machine setup and device tree parsing. This is called very
+ * early on the boot process.
+ */
+notrace void __init machine_init(unsigned long dt_ptr)
+{
+	struct boot_param_header *dtb = __va(dt_ptr);
+	struct boot_param_header *fdt = (struct boot_param_header *)_fdt_start;
+
+	/* interrupts must be masked */
+	set_creg(IER, 2);
+
+	/*
+	 * Set the Interrupt Service Table (IST) to the beginning of the
+	 * vector table.
+	 */
+	set_ist(_vectors_start);
+
+	lockdep_init();
+
+	/*
+	 * dtb is passed in from bootloader.
+	 * fdt is linked in blob.
+	 */
+	if (dtb && dtb != fdt)
+		fdt = dtb;
+
+	/* Do some early initialization based on the flat device tree */
+	early_init_devtree(fdt);
+
+	/* parse_early_param needs a boot_command_line */
+	strlcpy(boot_command_line, c6x_command_line, COMMAND_LINE_SIZE);
+	parse_early_param();
+}
+
+void __init setup_arch(char **cmdline_p)
+{
+	int bootmap_size;
+	struct memblock_region *reg;
+
+	printk(KERN_INFO "Initializing kernel\n");
+
+	/* Initialize command line */
+	*cmdline_p = c6x_command_line;
+
+	memblock_init();
+
+	memory_end = ram_end;
+	memory_end &= ~(PAGE_SIZE - 1);
+
+	if (mem_size && (PAGE_OFFSET + PAGE_ALIGN(mem_size)) < memory_end)
+		memory_end = PAGE_OFFSET + PAGE_ALIGN(mem_size);
+
+	/* add block that this kernel can use */
+	memblock_add(PAGE_OFFSET, memory_end - PAGE_OFFSET);
+
+	/* reserve kernel text/data/bss */
+	memblock_reserve(PAGE_OFFSET,
+			 PAGE_ALIGN((unsigned long)&_end - PAGE_OFFSET));
+
+	if (dma_size) {
+		/* align to cacheability granularity */
+		dma_size = CACHE_REGION_END(dma_size);
+
+		if (!dma_start)
+			dma_start = memory_end - dma_size;
+
+		/* align to cacheability granularity */
+		dma_start = CACHE_REGION_START(dma_start);
+
+		/* reserve DMA memory taken from kernel memory */
+		if (memblock_is_region_memory(dma_start, dma_size))
+			memblock_reserve(dma_start, dma_size);
+	}
+
+	memory_start = PAGE_ALIGN((unsigned int) &_end);
+
+	printk(KERN_INFO "Memory Start=%08lx, Memory End=%08lx\n",
+	       memory_start, memory_end);
+
+#ifdef CONFIG_BLK_DEV_INITRD
+	/*
+	 * Reserve initrd memory if in kernel memory.
+	 */
+	if (initrd_start < initrd_end)
+		if (memblock_is_region_memory(initrd_start,
+					      initrd_end - initrd_start))
+			memblock_reserve(initrd_start,
+					 initrd_end - initrd_start);
+#endif
+
+	init_mm.start_code = (unsigned long) &_stext;
+	init_mm.end_code   = (unsigned long) &_etext;
+	init_mm.end_data   = memory_start;
+	init_mm.brk        = memory_start;
+
+	/*
+	 * Give all the memory to the bootmap allocator,  tell it to put the
+	 * boot mem_map at the start of memory
+	 */
+	bootmap_size = init_bootmem_node(NODE_DATA(0),
+					 memory_start >> PAGE_SHIFT,
+					 PAGE_OFFSET >> PAGE_SHIFT,
+					 memory_end >> PAGE_SHIFT);
+	memblock_reserve(memory_start, bootmap_size);
+
+	memblock_analyze();
+	unflatten_device_tree();
+
+	c6x_cache_init();
+
+	/* Set the whole external memory as non-cacheable */
+	disable_caching(ram_start, ram_end - 1);
+
+	/* Set caching of external RAM used by Linux */
+	for_each_memblock(memory, reg)
+		enable_caching(CACHE_REGION_START(reg->base),
+			       CACHE_REGION_START(reg->base + reg->size - 1));
+
+#ifdef CONFIG_BLK_DEV_INITRD
+	/*
+	 * Enable caching for initrd which falls outside kernel memory.
+	 */
+	if (initrd_start < initrd_end) {
+		if (!memblock_is_region_memory(initrd_start,
+					       initrd_end - initrd_start))
+			enable_caching(CACHE_REGION_START(initrd_start),
+				       CACHE_REGION_START(initrd_end - 1));
+	}
+#endif
+
+	/*
+	 * Disable caching for dma coherent memory taken from kernel memory.
+	 */
+	if (dma_size && memblock_is_region_memory(dma_start, dma_size))
+		disable_caching(dma_start,
+				CACHE_REGION_START(dma_start + dma_size - 1));
+
+	/* Initialize the coherent memory allocator */
+	coherent_mem_init(dma_start, dma_size);
+
+	/*
+	 * Free all memory as a starting point.
+	 */
+	free_bootmem(PAGE_OFFSET, memory_end - PAGE_OFFSET);
+
+	/*
+	 * Then reserve memory which is already being used.
+	 */
+	for_each_memblock(reserved, reg) {
+		pr_debug("reserved - 0x%08x-0x%08x\n",
+			 (u32) reg->base, (u32) reg->size);
+		reserve_bootmem(reg->base, reg->size, BOOTMEM_DEFAULT);
+	}
+
+	max_low_pfn = PFN_DOWN(memory_end);
+	min_low_pfn = PFN_UP(memory_start);
+	max_mapnr = max_low_pfn - min_low_pfn;
+
+	/* Get kmalloc into gear */
+	paging_init();
+
+	/*
+	 * Probe for Device State Configuration Registers.
+	 * We have to do this early in case timer needs to be enabled
+	 * through DSCR.
+	 */
+	dscr_probe();
+
+	/* We do this early for timer and core clock frequency */
+	c64x_setup_clocks();
+
+	/* Get CPU info */
+	get_cpuinfo();
+
+#if defined(CONFIG_VT) && defined(CONFIG_DUMMY_CONSOLE)
+	conswitchp = &dummy_con;
+#endif
+}
+
+#define cpu_to_ptr(n) ((void *)((long)(n)+1))
+#define ptr_to_cpu(p) ((long)(p) - 1)
+
+static int show_cpuinfo(struct seq_file *m, void *v)
+{
+	int n = ptr_to_cpu(v);
+	struct cpuinfo_c6x *p = &per_cpu(cpu_data, n);
+
+	if (n == 0) {
+		seq_printf(m,
+			   "soc\t\t: %s\n"
+			   "soc revision\t: 0x%x\n"
+			   "soc cores\t: %d\n",
+			   c6x_soc_name, c6x_silicon_rev, c6x_num_cores);
+	}
+
+	seq_printf(m,
+		   "\n"
+		   "processor\t: %d\n"
+		   "cpu\t\t: %s\n"
+		   "core revision\t: %s\n"
+		   "core voltage\t: %s\n"
+		   "core id\t\t: %d\n"
+		   "mmu\t\t: %s\n"
+		   "fpu\t\t: %s\n"
+		   "cpu MHz\t\t: %u\n"
+		   "bogomips\t: %lu.%02lu\n\n",
+		   n,
+		   p->cpu_name, p->cpu_rev, p->cpu_voltage,
+		   p->core_id, p->mmu, p->fpu,
+		   (c6x_core_freq + 500000) / 1000000,
+		   (loops_per_jiffy/(500000/HZ)),
+		   (loops_per_jiffy/(5000/HZ))%100);
+
+	return 0;
+}
+
+static void *c_start(struct seq_file *m, loff_t *pos)
+{
+	return *pos < nr_cpu_ids ? cpu_to_ptr(*pos) : NULL;
+}
+static void *c_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	++*pos;
+	return NULL;
+}
+static void c_stop(struct seq_file *m, void *v)
+{
+}
+
+const struct seq_operations cpuinfo_op = {
+	c_start,
+	c_stop,
+	c_next,
+	show_cpuinfo
+};

arch/c6x/kernel/vectors.S

···
+;
+;  Port on Texas Instruments TMS320C6x architecture
+;
+;  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
+;  Author: Aurelien Jacquiot ([e-mail])
+;
+;  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.
+;
+;  This section handles all the interrupt vector routines.
+;  At RESET the processor sets up the DRAM timing parameters and
+;  branches to the label _c_int00 which handles initialization for the C code.
+;
+
+#define ALIGNMENT 5
+
+	.macro IRQVEC name, handler
+	.align ALIGNMENT
+	.hidden \name
+	.global \name
+\name:
+#ifdef CONFIG_C6X_BIG_KERNEL
+	STW	.D2T1	A0,*B15--[2]
+ ||	MVKL	.S1	\handler,A0
+	MVKH	.S1	\handler,A0
+	B	.S2X	A0
+	LDW	.D2T1	*++B15[2],A0
+	NOP	4
+	NOP
+	NOP
+	.endm
+#else /* CONFIG_C6X_BIG_KERNEL */
+	B	.S2	\handler
+	NOP
+	NOP
+	NOP
+	NOP
+	NOP
+	NOP
+	NOP
+	.endm
+#endif /* CONFIG_C6X_BIG_KERNEL */
+
+	   .sect ".vectors","ax"
+	   .align ALIGNMENT
+	   .global RESET
+	   .hidden RESET
+RESET:
+#ifdef CONFIG_C6X_BIG_KERNEL
+	   MVKL	.S1	_c_int00,A0		; branch to _c_int00
+	   MVKH	.S1	_c_int00,A0
+	   B	.S2X	A0
+#else
+	   B	.S2	_c_int00
+	   NOP
+	   NOP
+#endif
+	   NOP
+	   NOP
+	   NOP
+	   NOP
+	   NOP
+
+
+	   IRQVEC NMI,_nmi_handler		; NMI interrupt
+	   IRQVEC AINT,_bad_interrupt		; reserved
+	   IRQVEC MSGINT,_bad_interrupt		; reserved
+
+	   IRQVEC INT4,_int4_handler
+	   IRQVEC INT5,_int5_handler
+	   IRQVEC INT6,_int6_handler
+	   IRQVEC INT7,_int7_handler
+	   IRQVEC INT8,_int8_handler
+	   IRQVEC INT9,_int9_handler
+	   IRQVEC INT10,_int10_handler
+	   IRQVEC INT11,_int11_handler
+	   IRQVEC INT12,_int12_handler
+	   IRQVEC INT13,_int13_handler
+	   IRQVEC INT14,_int14_handler
+	   IRQVEC INT15,_int15_handler