[PATCH 1/2] powerpc/powernv: Add OPAL message log interface

[Stewart Smith]

Joel Stanley <joel at jms.id.au> writes:
> OPAL provides an in-memory circular buffer containing a message log
> populated with various runtime messages produced by the firmware.
>
> Provide a sysfs interface /sys/firmware/opal/messages for userspace to
> view the messages.

Acked-by: Stewart Smith <stewart at linux.vnet.ibm.com>

> Signed-off-by: Joel Stanley <joel at jms.id.au>
> ---
>  arch/powerpc/include/asm/opal.h                |  4 ++
>  arch/powerpc/platforms/powernv/Makefile        |  1 +
>  arch/powerpc/platforms/powernv/opal-messages.c | 97 ++++++++++++++++++++++++++
>  arch/powerpc/platforms/powernv/opal.c          |  4 +-
>  4 files changed, 105 insertions(+), 1 deletion(-)
>  create mode 100644 arch/powerpc/platforms/powernv/opal-messages.c
>
> diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
> index ffafab0..6aa757e 100644
> --- a/arch/powerpc/include/asm/opal.h
> +++ b/arch/powerpc/include/asm/opal.h
> @@ -729,6 +729,9 @@ typedef struct oppanel_line {
>  /* /sys/firmware/opal */
>  extern struct kobject *opal_kobj;
>
> +/* /ibm,opal */
> +extern struct device_node *opal_node;
> +
>  /* API functions */
>  int64_t opal_console_write(int64_t term_number, __be64 *length,
>  			   const uint8_t *buffer);
> @@ -918,6 +921,7 @@ extern void opal_flash_init(void);
>  extern int opal_elog_init(void);
>  extern void opal_platform_dump_init(void);
>  extern void opal_sys_param_init(void);
> +extern void opal_messages_init(void);
>
>  extern int opal_machine_check(struct pt_regs *regs);
>  extern bool opal_mce_check_early_recovery(struct pt_regs *regs);
> diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
> index f324ea0..e2ba418 100644
> --- a/arch/powerpc/platforms/powernv/Makefile
> +++ b/arch/powerpc/platforms/powernv/Makefile
> @@ -1,6 +1,7 @@
>  obj-y			+= setup.o opal-takeover.o opal-wrappers.o opal.o opal-async.o
>  obj-y			+= opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o
>  obj-y			+= rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o
> +obj-y			+= opal-messages.o
>
>  obj-$(CONFIG_SMP)	+= smp.o
>  obj-$(CONFIG_PCI)	+= pci.o pci-p5ioc2.o pci-ioda.o
> diff --git a/arch/powerpc/platforms/powernv/opal-messages.c b/arch/powerpc/platforms/powernv/opal-messages.c
> new file mode 100644
> index 0000000..3a863e8
> --- /dev/null
> +++ b/arch/powerpc/platforms/powernv/opal-messages.c
> @@ -0,0 +1,97 @@
> +/*
> + * PowerNV OPAL in-memory console interface
> + *
> + * Copyright 2014 IBM Corp.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#include <asm/io.h>
> +#include <asm/opal.h>
> +#include <linux/debugfs.h>
> +#include <linux/of.h>
> +#include <linux/types.h>
> +
> +/* OPAL in-memory console. Defined in OPAL source at core/console.c */
> +struct memcons {
> +	__be64 magic;
> +#define MEMCONS_MAGIC	0x6630696567726173L
> +	__be64 obuf_phys;
> +	__be64 ibuf_phys;
> +	__be32 obuf_size;
> +	__be32 ibuf_size;
> +	__be32 out_pos;
> +#define MEMCONS_OUT_POS_WRAP	0x80000000u
> +#define MEMCONS_OUT_POS_MASK	0x00ffffffu
> +	__be32 in_prod;
> +	__be32 in_cons;
> +};
> +
> +static ssize_t opal_messages_read(struct file *file, struct kobject *kobj,
> +	struct bin_attribute *bin_attr, char *to, loff_t pos, size_t count)
> +{
> +	struct memcons *mc = bin_attr->private;
> +	const char *conbuf;
> +	bool wrapped;
> +	size_t num_read;
> +	int out_pos;
> +
> +	if (!mc)
> +		return -ENODEV;
> +
> +	conbuf = phys_to_virt(be64_to_cpu(mc->obuf_phys));
> +	wrapped = be32_to_cpu(mc->out_pos) & MEMCONS_OUT_POS_WRAP;
> +	out_pos = be32_to_cpu(mc->out_pos) & MEMCONS_OUT_POS_MASK;
> +
> +	if (!wrapped) {
> +		num_read = memory_read_from_buffer(to, count, &pos, conbuf,
> +				out_pos);
> +	} else {
> +		num_read = memory_read_from_buffer(to, count, &pos,
> +				conbuf + out_pos,
> +				be32_to_cpu(mc->obuf_size) - out_pos);
> +
> +		if (num_read < 0)
> +			goto out;
> +
> +		num_read += memory_read_from_buffer(to + num_read,
> +				count - num_read, &pos, conbuf, out_pos);
> +	}
> +out:
> +	return num_read;
> +}
> +
> +static struct bin_attribute messages_attr = {
> +	.attr = {.name = "messages", .mode = 0444},
> +	.read = opal_messages_read
> +};
> +
> +void __init opal_messages_init(void)
> +{
> +	u64 mcaddr;
> +	struct memcons *mc;
> +
> +	if (of_property_read_u64(opal_node, "ibm,opal-memcons", &mcaddr)) {
> +		pr_warn("OPAL: Property ibm,opal-memcons not found, no message log\n");
> +		return;
> +	}
> +
> +	mc = phys_to_virt(mcaddr);
> +	if (!mc) {
> +		pr_warn("OPAL: memory console address is invalid\n");
> +		return;
> +	}
> +
> +	if (be64_to_cpu(mc->magic) != MEMCONS_MAGIC) {
> +		pr_warn("OPAL: memory console version is invalid\n");
> +		return;
> +	}
> +
> +	messages_attr.private = mc;
> +
> +	if (sysfs_create_bin_file(opal_kobj, &messages_attr) != 0)
> +		pr_warn("OPAL: sysfs file creation failed\n");
> +}
> diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
> index e92f2f6..2bc032a 100644
> --- a/arch/powerpc/platforms/powernv/opal.c
> +++ b/arch/powerpc/platforms/powernv/opal.c
> @@ -46,7 +46,7 @@ struct mcheck_recoverable_range {
>  static struct mcheck_recoverable_range *mc_recoverable_range;
>  static int mc_recoverable_range_len;
>
> -static struct device_node *opal_node;
> +struct device_node *opal_node;
>  static DEFINE_SPINLOCK(opal_write_lock);
>  extern u64 opal_mc_secondary_handler[];
>  static unsigned int *opal_irqs;
> @@ -574,6 +574,8 @@ static int __init opal_init(void)
>  		opal_platform_dump_init();
>  		/* Setup system parameters interface */
>  		opal_sys_param_init();
> +		/* Setup message log interface. */
> +		opal_messages_init();
>  	}
>
>  	return 0;
> -- 
> 1.9.1