From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: [PATCH v1 3/6] x86/boot: Add MMIO byte accessors
Date: Sun, 14 Jan 2018 16:32:51 +0200 [thread overview]
Message-ID: <20180114143254.15429-3-andriy.shevchenko@linux.intel.com> (raw)
In-Reply-To: <20180114143254.15429-1-andriy.shevchenko@linux.intel.com>
readb() and writeb() would help to access serial device
via MMIO address space.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
arch/x86/boot/boot.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index 7e6ac187275c..09f6829f2778 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -79,6 +79,18 @@ static inline void io_delay(void)
asm volatile("outb %%al,%0" : : "dN" (DELAY_PORT));
}
+static inline u8 readb(const volatile void __iomem *addr)
+{
+ u8 v;
+ asm volatile("movb %1,%0" : "=q" (v) : "m" (*(volatile u8 __force *)addr));
+ return v;
+}
+
+static inline void writeb(u8 v, volatile void __iomem *addr)
+{
+ asm volatile("movb %0,%1" : : "q" (v), "m" (*(volatile u8 __force *)addr));
+}
+
/* These functions are used to reference data in other segments. */
static inline u16 ds(void)
--
2.15.1
next prev parent reply other threads:[~2018-01-14 14:33 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-14 14:32 [PATCH v1 1/6] x86/boot: Convert early_serial_base to unsigned long Andy Shevchenko
2018-01-14 14:32 ` [PATCH v1 2/6] x86/boot: Introduce helpers for serial I/O Andy Shevchenko
2018-01-14 14:32 ` Andy Shevchenko [this message]
2018-01-14 14:32 ` [PATCH v1 4/6] x86/boot: Assume MMIO if serial base address supplied via earlyprintk Andy Shevchenko
2018-01-16 3:13 ` Ingo Molnar
2018-01-16 10:55 ` Andy Shevchenko
2018-01-16 15:55 ` Ingo Molnar
2018-05-03 10:45 ` Andy Shevchenko
2018-01-14 14:32 ` [PATCH v1 5/6] x86/boot: Allow longer parameter list for earlyprintk Andy Shevchenko
2018-01-16 3:11 ` Ingo Molnar
2018-01-16 10:57 ` Andy Shevchenko
2018-01-16 15:51 ` Ingo Molnar
2018-05-03 11:48 ` Andy Shevchenko
2018-01-14 14:32 ` [PATCH v1 6/6] x86/boot: Support nocfg parameter " Andy Shevchenko
2018-01-16 3:12 ` Ingo Molnar
2018-01-16 11:00 ` Andy Shevchenko
2018-01-16 15:53 ` Ingo Molnar
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