From: Lee Jones <lee.jones@linaro.org>
To: Sergey.Semin@baikalelectronics.ru
Cc: Serge Semin <fancer.lancer@gmail.com>,
Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Paul Burton <paulburton@kernel.org>,
Ralf Baechle <ralf@linux-mips.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] mfd: Add Baikal-T1 Boot Controller driver
Date: Wed, 25 Mar 2020 10:09:40 +0000 [thread overview]
Message-ID: <20200325100940.GI442973@dell> (raw)
In-Reply-To: <20200306130614.696EF8030704@mail.baikalelectronics.ru>
On Fri, 06 Mar 2020, Sergey.Semin@baikalelectronics.ru wrote:
> From: Serge Semin <Sergey.Semin@baikalelectronics.ru>
>
> Baikal-T1 Boot Controller is an IP block embedded into the SoC and
> responsible for the chip proper pre-initialization and further
> booting up from some memory device. From the Linux kernel point of view
> it's just a multi-functional device, which exports three physically mapped
> ROMs and a single SPI controller.
>
> Primarily the ROMs are intended to be used for transparent access of
> the memory devices with system bootup code. First ROM device is an
> embedded into the SoC firmware, which is supposed to be used just for
> the chip debug and tests. Second ROM device provides a MMIO-based
> access to an external SPI flash. Third ROM mirrors either the Internal
> or SPI ROM region, depending on the state of the external BOOTCFG_{0,1}
> chip pins selecting the system boot device.
>
> External SPI flash can be also accessed by the DW APB SSI SPI controller
> embedded into the Baikal-T1 Boot Controller. In this case the memory mapped
> SPI flash region shouldn't be accessed.
>
> Taking into account all the peculiarities described above, we created
> an MFD-based driver for the Baikal-T1 controller. Aside from ordinary
> OF-based sub-device registration it also provides a simple API to
> serialize an access to the external SPI flash from either the MMIO-based
> SPI interface or embedded SPI controller.
Not sure why this is being classified as an MFD.
This is clearly 'just' a memory device.
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Paul Burton <paulburton@kernel.org>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> ---
> drivers/mfd/Kconfig | 13 ++
> drivers/mfd/Makefile | 1 +
> drivers/mfd/bt1-boot-ctl.c | 345 +++++++++++++++++++++++++++++++
> include/linux/mfd/bt1-boot-ctl.h | 46 +++++
> 4 files changed, 405 insertions(+)
> create mode 100644 drivers/mfd/bt1-boot-ctl.c
> create mode 100644 include/linux/mfd/bt1-boot-ctl.h
[...]
> diff --git a/drivers/mfd/bt1-boot-ctl.c b/drivers/mfd/bt1-boot-ctl.c
> new file mode 100644
> index 000000000000..9e3cd47a2e7a
> --- /dev/null
> +++ b/drivers/mfd/bt1-boot-ctl.c
> @@ -0,0 +1,345 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
> + *
> + * Authors:
> + * Serge Semin <Sergey.Semin@baikalelectronics.ru>
> + *
> + * Baikal-T1 Boot Controller driver.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/clk.h>
> +#include <linux/mutex.h>
> +#include <linux/mfd/core.h>
Despite including the MFD API, I don't see it being used at all.
> +#include <linux/mfd/bt1-boot-ctl.h>
[...]
> +static inline u32 bc_read(void __iomem *reg)
> +{
> + return readl(reg);
> +}
> +
> +static inline void bc_write(void __iomem *reg, u32 data)
> +{
> + writel(data, reg);
> +}
Abstraction for the sake of abstraction is generally discouraged.
[...]
> +static int bc_register_devices(struct bt1_bc *bc)
> +{
> + int ret;
> +
> + ret = devm_of_platform_populate(bc->dev);
> + if (ret)
> + dev_err(bc->dev, "Failed to add sub-devices\n");
> +
> + return ret;
> +}
You can call devm_of_platform_populate() from anywhere.
Doesn't have to be an MFD.
[...]
--
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
next prev parent reply other threads:[~2020-03-25 10:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200306130528.9973-1-Sergey.Semin@baikalelectronics.ru>
2020-03-06 13:05 ` [PATCH 1/2] dt-bindings: mfd: Add Baikal-T1 Boot Controller bindings Sergey.Semin
2020-03-09 18:07 ` Rob Herring
[not found] ` <20200309180734.A303C80307C7@mail.baikalelectronics.ru>
2020-03-13 15:09 ` Sergey Semin
2020-03-06 13:05 ` [PATCH 2/2] mfd: Add Baikal-T1 Boot Controller driver Sergey.Semin
2020-03-25 10:09 ` Lee Jones [this message]
2020-03-25 16:55 ` Sergey Semin
2020-03-26 9:13 ` Lee Jones
2020-03-26 11:32 ` Sergey Semin
2020-03-27 9:01 ` Lee Jones
2020-03-27 10:25 ` Miquel Raynal
2020-03-27 16:36 ` Sergey Semin
2020-03-27 10:45 ` Sergey Semin
2020-03-10 1:11 ` [PATCH 0/2] mfd: Add Baikal-T1 SoC " Sergey Semin
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