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Commit b846c10d authored by Wu Zhangjin's avatar Wu Zhangjin Committed by Ralf Baechle
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MIPS: Lemote 2F: Ensure atomic execution of _rdmsr and _wrmsr 



On Lemote 2F CS5536 MSRs are accessed through a index / data register pair.
The access sequence must be protected by a spinlock to be atomic.

Without this rebooting in fs2f_reboot() may fail.

Signed-off-by: default avatarWu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: David Daney <ddaney@caviumnetworks.com>
Patchwork: http://patchwork.linux-mips.org/patch/1058/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 52553664

arch/mips/pci/ops-loongson2.c

+10 −0
Original line number Diff line number Diff line
@@ -180,15 +180,21 @@ struct pci_ops loongson_pci_ops = { 
};



#ifdef CONFIG_CS5536

DEFINE_RAW_SPINLOCK(msr_lock);



void _rdmsr(u32 msr, u32 *hi, u32 *lo)

{

	struct pci_bus bus = {

		.number = PCI_BUS_CS5536

	};

	u32 devfn = PCI_DEVFN(PCI_IDSEL_CS5536, 0);

	unsigned long flags;



	raw_spin_lock_irqsave(&msr_lock, flags);

	loongson_pcibios_write(&bus, devfn, PCI_MSR_ADDR, 4, msr);

	loongson_pcibios_read(&bus, devfn, PCI_MSR_DATA_LO, 4, lo);

	loongson_pcibios_read(&bus, devfn, PCI_MSR_DATA_HI, 4, hi);

	raw_spin_unlock_irqrestore(&msr_lock, flags);

}

EXPORT_SYMBOL(_rdmsr);
@@ -198,9 +204,13 @@ void _wrmsr(u32 msr, u32 hi, u32 lo) 
		.number = PCI_BUS_CS5536

	};

	u32 devfn = PCI_DEVFN(PCI_IDSEL_CS5536, 0);

	unsigned long flags;



	raw_spin_lock_irqsave(&msr_lock, flags);

	loongson_pcibios_write(&bus, devfn, PCI_MSR_ADDR, 4, msr);

	loongson_pcibios_write(&bus, devfn, PCI_MSR_DATA_LO, 4, lo);

	loongson_pcibios_write(&bus, devfn, PCI_MSR_DATA_HI, 4, hi);

	raw_spin_unlock_irqrestore(&msr_lock, flags);

}

EXPORT_SYMBOL(_wrmsr);

#endif