| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <45f0beda-08a6-5db7-a8f1-a63b6e879b81@ti.com>
Date: Fri, 5 Jul 2019 00:05:58 +0530
From: Vignesh Raghavendra <vigneshr@...com>
To: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
Boris Brezillon <bbrezillon@...nel.org>,
Marek Vasut <marek.vasut@...il.com>,
Richard Weinberger <richard@....at>,
Rob Herring <robh+dt@...nel.org>
CC: <linux-mtd@...ts.infradead.org>,
Miquel Raynal <miquel.raynal@...tlin.com>,
<devicetree@...r.kernel.org>, Mason Yang <masonccyang@...c.com.tw>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>,
Tokunori Ikegami <ikegami.t@...il.com>
Subject: Re: [PATCH v8 3/5] mtd: Add support for HyperBus memory devices
On 03-Jul-19 11:44 PM, Sergei Shtylyov wrote:
> Hello!
>
> On 07/03/2019 07:41 AM, Vignesh Raghavendra wrote:
>
>>>> Cypress' HyperBus is Low Signal Count, High Performance Double Data Rate
>>>> Bus interface between a host system master and one or more slave
>>>> interfaces. HyperBus is used to connect microprocessor, microcontroller,
>>>> or ASIC devices with random access NOR flash memory (called HyperFlash)
>>>> or self refresh DRAM (called HyperRAM).
>>>>
>>>> Its a 8-bit data bus (DQ[7:0]) with Read-Write Data Strobe (RWDS)
>>>> signal and either Single-ended clock(3.0V parts) or Differential clock
>>>> (1.8V parts). It uses ChipSelect lines to select b/w multiple slaves.
>>>> At bus level, it follows a separate protocol described in HyperBus
>>>> specification[1].
>>>>
>>>> HyperFlash follows CFI AMD/Fujitsu Extended Command Set (0x0002) similar
>>>> to that of existing parallel NORs. Since HyperBus is x8 DDR bus,
>>>> its equivalent to x16 parallel NOR flash with respect to bits per clock
>>>> cycle. But HyperBus operates at >166MHz frequencies.
>>>> HyperRAM provides direct random read/write access to flash memory
>>>> array.
>>>>
>>>> But, HyperBus memory controllers seem to abstract implementation details
>>>> and expose a simple MMIO interface to access connected flash.
>>>>
>>>> Add support for registering HyperFlash devices with MTD framework. MTD
>>>> maps framework along with CFI chip support framework are used to support
>>>> communicating with flash.
>>>>
>>>> Framework is modelled along the lines of spi-nor framework. HyperBus
>>>> memory controller (HBMC) drivers calls hyperbus_register_device() to
>>>> register a single HyperFlash device. HyperFlash core parses MMIO access
>>>> information from DT, sets up the map_info struct, probes CFI flash and
>>>> registers it with MTD framework.
>>>>
>>>> Some HBMC masters need calibration/training sequence[3] to be carried
>>>> out, in order for DLL inside the controller to lock, by reading a known
>>>> string/pattern. This is done by repeatedly reading CFI Query
>>>> Identification String. Calibration needs to be done before trying to detect
>>>> flash as part of CFI flash probe.
>>>>
>>>> HyperRAM is not supported at the moment.
>>>>
>>>> HyperBus specification can be found at[1]
>>>> HyperFlash datasheet can be found at[2]
>>>>
>>>> [1] https://www.cypress.com/file/213356/download
>>>> [2] https://www.cypress.com/file/213346/download
>>>> [3] http://www.ti.com/lit/ug/spruid7b/spruid7b.pdf
>>>> Table 12-5741. HyperFlash Access Sequence
>>>>
>>>> Signed-off-by: Vignesh Raghavendra <vigneshr@...com>
>>> [...]
>>>
>>> I have at least created my HyperBus driver and unfortunately I'm having serious
>
> At last. :-)
>
So, I guess driver works for limited memory size?
>>> issues with the design of the support core (see below)...
>>>
>>> [...]
>>>> diff --git a/drivers/mtd/hyperbus/hyperbus-core.c b/drivers/mtd/hyperbus/hyperbus-core.c
>>>> new file mode 100644
>>>> index 000000000000..63a9e64895bc
>>>> --- /dev/null
>>>> +++ b/drivers/mtd/hyperbus/hyperbus-core.c
>>>> @@ -0,0 +1,154 @@
>>> [...]
>>>> +int hyperbus_register_device(struct hyperbus_device *hbdev)
>>>> +{
>>>> + const struct hyperbus_ops *ops;
>>>> + struct hyperbus_ctlr *ctlr;
>>>> + struct device_node *np;
>>>> + struct map_info *map;
>>>> + struct resource res;
>>>> + struct device *dev;
>>>> + int ret;
>>>> +
>>>> + if (!hbdev || !hbdev->np || !hbdev->ctlr || !hbdev->ctlr->dev) {
>>>> + pr_err("hyperbus: please fill all the necessary fields!\n");
>>>> + return -EINVAL;
>>>> + }
>>>> +
>>>> + np = hbdev->np;
>>>> + ctlr = hbdev->ctlr;
>>>> + if (!of_device_is_compatible(np, "cypress,hyperflash"))
>>>> + return -ENODEV;
>>>> +
>>>> + hbdev->memtype = HYPERFLASH;
>>>> +
>>>> + ret = of_address_to_resource(np, 0, &res);
>>>
>>> Hm, I doubt that the HB devices are wholly mapped into memory space, that seems
>>> like a property of the HB controller. In my case, the flash device in the DT has
>>> only single-cell "reg" prop (equal to the chip select #). Then this function returns
>>> -EINVAL and the registration fails. Also, in my case such mapping is R/O, not R/W.
>>>
>>
>> You could declare R/O MMIO region in controla and set up a translation using ranges
>> from slave's reg CS based reg mapping like:
>
> No, not all HB controllers work the same (simple) way as yours. In case of RPC-IF,
> the direct read map is a 64 MiB window into a possibly larger flash chip, it has a
> register supplying address bits 25:31...
Okay, this limitation was not made clear earlier. I thought RPC-IF also
supported MMIO accesses for all reads
I will look into changes needed to support HB controllers that don't
have MMIO interface next week.
Regards
Vignesh
>
>> + hbmc: hyperbus@...34000 {
>> + compatible = "ti,am654-hbmc";
>> + reg = <0x0 0x47034000 0x0 0x100>,
>> + <0x5 0x00000000 0x1 0x0000000>;
>> + #address-cells = <2>;
>> + #size-cells = <1>;
>> + ranges = <0x0 0x0 0x5 0x00000000 0x4000000>, /* CS0 - 64MB */
>> + <0x1 0x0 0x5 0x04000000 0x4000000>; /* CS1 - 64MB */
>> +
>> + /* Slave flash node */
>> + flash@0,0 {
>> + compatible = "cypress,hyperflash", "cfi-flash";
>> + reg = <0x0 0x0 0x4000000>;
>> + };
>> + };
>>
>> If you use just CS# how would you handle CS to MMIO region mapping?
>> Does both CS use the same MMIO base for reads?
>
> The RPC-IF HF mode only has a single CS signal.
>
I see...
> [...]
>
> MBR, Sergei
>
Regards
Vignesh
Powered by blists - more mailing lists