From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
To: Vignesh Raghavendra <vigneshr@ti.com>,
David Woodhouse <dwmw2@infradead.org>,
Brian Norris <computersforpeace@gmail.com>,
Boris Brezillon <bbrezillon@kernel.org>,
Marek Vasut <marek.vasut@gmail.com>,
Richard Weinberger <richard@nod.at>,
Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
tudor.ambarus@microchip.com,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
nsekhar@ti.com, linux-kernel@vger.kernel.org,
linux-mtd@lists.infradead.org,
Mason Yang <masonccyang@mxic.com.tw>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC PATCH v2 3/5] mtd: Add support for Hyperbus memory devices
Date: Tue, 26 Mar 2019 10:51:23 +0300 [thread overview]
Message-ID: <02dfcf5d-f7f8-f33a-22b2-462ea92b0702@cogentembedded.com> (raw)
In-Reply-To: <98e1e3ad-75d3-670f-bcf7-27389cc60a98@cogentembedded.com>
On 25.03.2019 23:13, Sergei Shtylyov wrote:
>> Cypress' Hyperbus is Low Signal Count, High Performance Double Data Rate
>
> It's HyperBus, according to the spec...
>
>> 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].
>
> HyperBus.
>> 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 wrt 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
>
> HyperBus.
>
>> and expose a simple MMIO interface to access connected flash.
>>
>> Add support for registering Hyperflash devices with MTD framework. MTD
>
> HyperFlash.
>
>> 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
>
> HyperBus.
>
>> memory controller (HBMC) drivers calls hyperbus_register_device() to
>> register a single Hyperflash device. Hyperflash core parses MMIO access
>
> HyperFlash.
>
>> 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]
>
> HyperBus & HyperFlash.
>
>> [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@ti.com>
> [...]
>> diff --git a/drivers/mtd/hyperbus/hyperbus-core.c b/drivers/mtd/hyperbus/hyperbus-core.c
>> new file mode 100644
>> index 000000000000..4c2876c367fc
>> --- /dev/null
>> +++ b/drivers/mtd/hyperbus/hyperbus-core.c
>> @@ -0,0 +1,183 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +//
>> +// Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
>> +// Author: Vignesh Raghavendra <vigneshr@ti.com>
>> +
>> +#include <linux/err.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/mtd/hyperbus.h>
>> +#include <linux/mtd/map.h>
>> +#include <linux/mtd/mtd.h>
>> +#include <linux/mtd/cfi.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/types.h>
>> +
>> +#define HYPERBUS_CALIB_COUNT 25
>
> As I said, this seems platform specific...
>
> [...]
>> +/* Default calibration routine for use by Hyperbus controller.
>
> No, there should be easy opt-out from the calibration method.
> Currently, the driver will have to define its own calibrate method, even
> if does't need any calibration...
Nevermind -- the method ptr can be NULL, of course, so there's easy opt-out...
[...]
MBR, Sergei
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next prev parent reply other threads:[~2019-03-26 7:52 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-21 17:45 [RFC PATCH v2 0/5] MTD: Add Initial Hyperbus support Vignesh Raghavendra
2019-03-21 17:45 ` [RFC PATCH v2 1/5] mtd: cfi_cmdset_0002: Add support for polling status register Vignesh Raghavendra
2019-03-21 18:11 ` Joakim Tjernlund
2019-03-25 12:57 ` Vignesh Raghavendra
2019-03-25 13:51 ` Joakim Tjernlund
2019-03-25 17:06 ` Vignesh Raghavendra
2019-03-25 17:24 ` Joakim Tjernlund
2019-04-02 9:03 ` Vignesh Raghavendra
2019-03-24 16:23 ` Sergei Shtylyov
2019-03-21 17:45 ` [RFC PATCH v2 2/5] dt-bindings: mtd: Add binding documentation for Hyperbus memory devices Vignesh Raghavendra
2019-03-24 16:18 ` Sergei Shtylyov
2019-03-25 13:10 ` Vignesh Raghavendra
2019-03-21 17:45 ` [RFC PATCH v2 3/5] mtd: Add support " Vignesh Raghavendra
2019-03-25 20:13 ` Sergei Shtylyov
2019-03-26 7:51 ` Sergei Shtylyov [this message]
2019-03-21 17:45 ` [RFC PATCH v2 4/5] dt-bindings: mtd: Add bindings for TI's AM654 Hyperbus memory controller Vignesh Raghavendra
2019-03-21 17:45 ` [RFC PATCH v2 5/5] mtd: hyperbus: Add driver for TI's " Vignesh Raghavendra
2019-03-26 10:40 ` Sergei Shtylyov
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