Re: [PATCH v3 2/2] FPGA: Add TS-7300 FPGA manager

From: Florian Fainelli
Date: Wed Dec 14 2016 - 15:01:02 EST

On 12/13/2016 10:07 PM, Moritz Fischer wrote:
> Hi Florian,
>
> On Tue, Dec 13, 2016 at 6:35 PM, Florian Fainelli <f.fainelli@xxxxxxxxx> wrote:
>> Add support for loading bitstreams on the Altera Cyclone II FPGA
>> populated on the TS-7300 board. This is done through the configuration
>> and data registers offered through a memory interface between the EP93xx
>> SoC and the FPGA via an intermediate CPLD device.
>>
>> The EP93xx SoC on the TS-7300 does not have direct means of configuring
>> the on-board FPGA other than by using the special memory mapped
>> interface to the CPLD. No other entity on the system can control the
>> FPGA bitstream.
>>
>> Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
>> ---
>> drivers/fpga/Kconfig | 7 ++
>> drivers/fpga/Makefile | 1 +
>> drivers/fpga/ts73xx-fpga.c | 163 +++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 171 insertions(+)
>> create mode 100644 drivers/fpga/ts73xx-fpga.c
>>
>> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
>> index ce861a2853a4..d9cbef60db80 100644
>> --- a/drivers/fpga/Kconfig
>> +++ b/drivers/fpga/Kconfig
>> @@ -33,6 +33,13 @@ config FPGA_MGR_SOCFPGA_A10
>> help
>> FPGA manager driver support for Altera Arria10 SoCFPGA.
>>
>> +config FPGA_MGR_TS73XX
>> + tristate "Technologic Systems TS-73xx SBC FPGA Manager"
>> + depends on ARCH_EP93XX && MACH_TS72XX
>> + help
>> + FPGA manager driver support for the Altera Cyclone II FPGA
>> + present on the TS-73xx SBC boards.
>> +
>> config FPGA_MGR_ZYNQ_FPGA
>> tristate "Xilinx Zynq FPGA"
>> depends on ARCH_ZYNQ || COMPILE_TEST
>> diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
>> index 8df07bcf42a6..a1160169e6d9 100644
>> --- a/drivers/fpga/Makefile
>> +++ b/drivers/fpga/Makefile
>> @@ -8,6 +8,7 @@ obj-$(CONFIG_FPGA) += fpga-mgr.o
>> # FPGA Manager Drivers
>> obj-$(CONFIG_FPGA_MGR_SOCFPGA) += socfpga.o
>> obj-$(CONFIG_FPGA_MGR_SOCFPGA_A10) += socfpga-a10.o
>> +obj-$(CONFIG_FPGA_MGR_TS73XX) += ts73xx-fpga.o
>> obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA) += zynq-fpga.o
>>
>> # FPGA Bridge Drivers
>> diff --git a/drivers/fpga/ts73xx-fpga.c b/drivers/fpga/ts73xx-fpga.c
>> new file mode 100644
>> index 000000000000..38d78d8c6b1e
>> --- /dev/null
>> +++ b/drivers/fpga/ts73xx-fpga.c
>> @@ -0,0 +1,163 @@
>> +/*
>> + * Technologic Systems TS-73xx SBC FPGA loader
>> + *
>> + * Copyright (C) 2016 Florian Fainelli <f.fainelli@xxxxxxxxx>
>> + *
>> + * FPGA Manager Driver for the on-board Altera Cyclone II FPGA found on
>> + * TS-7300, heavily based on load_fpga.c in their vendor tree.
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; version 2 of the License.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/delay.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/string.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/fpga/fpga-mgr.h>
>> +
>> +#define TS73XX_FPGA_DATA_REG 0
>> +#define TS73XX_FPGA_CONFIG_REG 1
>> +
>> +#define TS73XX_FPGA_WRITE_DONE 0x1
>> +#define TS73XX_FPGA_WRITE_DONE_TIMEOUT 1000 /* us */
>> +#define TS73XX_FPGA_RESET 0x2
>> +#define TS73XX_FPGA_RESET_LOW_DELAY 30 /* us */
>> +#define TS73XX_FPGA_RESET_HIGH_DELAY 80 /* us */
>> +#define TS73XX_FPGA_LOAD_OK 0x4
>> +#define TS73XX_FPGA_CONFIG_LOAD 0x8
>> +
>> +struct ts73xx_fpga_priv {
>> + void __iomem *io_base;
>> + struct device *dev;
>> +};
>> +
>> +static enum fpga_mgr_states ts73xx_fpga_state(struct fpga_manager *mgr)
>> +{
>> + return FPGA_MGR_STATE_UNKNOWN;
>> +}
>> +
>> +static int ts73xx_fpga_write_init(struct fpga_manager *mgr,
>> + struct fpga_image_info *info,
>> + const char *buf, size_t count)
>> +{
>> + struct ts73xx_fpga_priv *priv = mgr->priv;
>> +
>> + /* Reset the FPGA */
>> + writeb(0, priv->io_base + TS73XX_FPGA_CONFIG_REG);
>> + udelay(TS73XX_FPGA_RESET_LOW_DELAY);
>> + writeb(TS73XX_FPGA_RESET, priv->io_base + TS73XX_FPGA_CONFIG_REG);
>> + udelay(TS73XX_FPGA_RESET_HIGH_DELAY);
>> +
>> + return 0;
>> +}
>> +
>> +static int ts73xx_fpga_write(struct fpga_manager *mgr, const char *buf,
>> + size_t count)
>> +{
>> + struct ts73xx_fpga_priv *priv = mgr->priv;
>> + size_t i = 0;
>> + int ret;
>> + u8 reg;
>> +
>> + while (count--) {
>> + ret = readb_poll_timeout(priv->io_base + TS73XX_FPGA_CONFIG_REG,
>> + reg, !(reg & TS73XX_FPGA_WRITE_DONE),
>> + 1, TS73XX_FPGA_WRITE_DONE_TIMEOUT);
>> + if (ret < 0)
>> + return ret;
>> +
>> + writeb(buf[i], priv->io_base + TS73XX_FPGA_DATA_REG);
>> + i++;
>> + }
>> +
>
> <snip>
>> + usleep_range(1000, 2000);
>> + reg = readb(priv->io_base + TS73XX_FPGA_CONFIG_REG);
>> + reg |= TS73XX_FPGA_CONFIG_LOAD;
>> + writeb(reg, priv->io_base + TS73XX_FPGA_CONFIG_REG);
>> + usleep_range(1000, 2000);
>
> </snip>
>
> Just to clarify is this block what triggers the actual write? I'm asking because
> I'm wondering if in the current implementation the ts73xx_fpga_write() function
> can be called multiple times in your implementation before you finally get to
> the write complete callback.

My understanding is that, yes, this triggers the final write. You are
right that ts73xx_fpga_write() can be called multiple times. It sounds
like what my write_complete function does right now is just return that
we successfully completed the bistream write, but this snippet that you
are quoting should actually be moved into write_complete.

Does that sound reasonable?
--
Florian