linux-kernel - Re: [PATCH v2 1/3] MIPS: Loongson: Get host bridge information

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Date:   Tue, 24 Mar 2020 18:02:38 +0800
From:   Jiaxun Yang <jiaxun.yang@...goat.com>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Huacai Chen <chenhc@...ote.com>
CC:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        Xuefeng Li <lixuefeng@...ngson.cn>
Subject: Re: [PATCH v2 1/3] MIPS: Loongson: Get host bridge information



于 2020年3月24日 GMT+08:00 下午5:58:33, Tiezhu Yang <yangtiezhu@...ngson.cn> 写到:
>On 03/24/2020 03:36 PM, Jiaxun Yang wrote:
>>
>> 于 2020年3月23日 GMT+08:00 上午10:59:13, Tiezhu Yang
><yangtiezhu@...ngson.cn> 写到:
>>> Read the address of HyperTransport Configuration Space to get the
>>> vendor ID
>>> and device ID of bridge chip, and then we can distinguish various
>types
>>> of
>>> bridge chip such as Loongson 7A1000 or AMD RS780E.
>>>
>>> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
>>> ---
>>> arch/mips/include/asm/mach-loongson64/boot_param.h |  6 ++++++
>>> arch/mips/loongson64/env.c                         | 16
>>> ++++++++++++++++
>>> 2 files changed, 22 insertions(+)
>>>
>>> diff --git a/arch/mips/include/asm/mach-loongson64/boot_param.h
>>> b/arch/mips/include/asm/mach-loongson64/boot_param.h
>>> index 8c286be..5e8c70d 100644
>>> --- a/arch/mips/include/asm/mach-loongson64/boot_param.h
>>> +++ b/arch/mips/include/asm/mach-loongson64/boot_param.h
>>> @@ -190,6 +190,11 @@ struct boot_params {
>>> 	struct efi_reset_system_t reset_system;
>>> };
>>>
>>> +enum loongson_bridge_type {
>>> +	RS780E = 1,
>>> +	LS7A1000 = 2
>>> +};
>>> +
>>> struct loongson_system_configuration {
>>> 	u32 nr_cpus;
>>> 	u32 nr_nodes;
>>> @@ -198,6 +203,7 @@ struct loongson_system_configuration {
>>> 	u16 boot_cpu_id;
>>> 	u16 reserved_cpus_mask;
>>> 	enum loongson_cpu_type cputype;
>>> +	enum loongson_bridge_type bridgetype;
>>> 	u64 ht_control_base;
>>> 	u64 pci_mem_start_addr;
>>> 	u64 pci_mem_end_addr;
>>> diff --git a/arch/mips/loongson64/env.c b/arch/mips/loongson64/env.c
>>> index 0daeb7b..42542c7 100644
>>> --- a/arch/mips/loongson64/env.c
>>> +++ b/arch/mips/loongson64/env.c
>>> @@ -19,6 +19,8 @@
>>> #include <boot_param.h>
>>> #include <workarounds.h>
>>>
>>> +#define HT1_LO_BUS_CONFIG_BASE	0x90000efdfe000000
>>> +
>>> u32 cpu_clock_freq;
>>> EXPORT_SYMBOL(cpu_clock_freq);
>>> struct efi_memory_map_loongson *loongson_memmap;
>>> @@ -42,6 +44,8 @@ void __init prom_init_env(void)
>>> 	struct system_loongson *esys;
>>> 	struct efi_cpuinfo_loongson *ecpu;
>>> 	struct irq_source_routing_table *eirq_source;
>>> +	u32 id;
>>> +	u16 vendor, device;
>>>
>>> 	/* firmware arguments are initialized in head.S */
>>> 	boot_p = (struct boot_params *)fw_arg2;
>>> @@ -155,4 +159,16 @@ void __init prom_init_env(void)
>>> 		memcpy(loongson_sysconf.sensors, esys->sensors,
>>> 			sizeof(struct sensor_device) * loongson_sysconf.nr_sensors);
>>> 	pr_info("CpuClock = %u\n", cpu_clock_freq);
>>> +
>>> +	id = readl((u32 *)HT1_LO_BUS_CONFIG_BASE);
>> Is that pointer cast required?
>
>Yes, otherwise it will compile failed:
>arch/mips/loongson64/env.c:163:13: error: passing argument 1 of ‘readl’

I don't like it through....
Can we cast it in macro?
At least it should be void __iomem *.


>
>makes pointer from integer without a cast [-Werror]
>   id = readl(HT1_LO_BUS_CONFIG_BASE);
>              ^
>>
>> And you'd better add a comment here like
>> /* Read HT PCI 00:00:00 Host Bridge's ID to detect bridge model */
>> Otherwise it's hard for others to understand what you are doing.
>
>OK, I will do it.
>
>>
>>> +	vendor = id & 0xffff;
>>> +	device = (id >> 16) & 0xffff;
>>> +
>>> +	if (vendor == 0x0014 && device == 0x7a00) {
>> Please confirm with hardware design guys that bridge chip in future
>will have different dev ID.
>
>Yes, it maybe have a new device ID for the new bridge chip.
>
>>
>> Thanks.
>>
>>> +		pr_info("The bridge chip is Loongson 7A1000\n");
>>> +		loongson_sysconf.bridgetype = LS7A1000;
>>> +	} else {
>>> +		pr_info("The bridge chip is AMD RS780E or SR5690\n");
>>> +		loongson_sysconf.bridgetype = RS780E;
>>> +	}
>>> }

-- 
Jiaxun Yang