Messages in this thread | | | Date | Wed, 25 Mar 2020 10:09:40 +0000 | From | Lee Jones <> | Subject | Re: [PATCH 2/2] mfd: Add Baikal-T1 Boot Controller driver |
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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
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> 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>
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> +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.
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> +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.
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-- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
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