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

[Florian Fainelli <f.fainelli@gmail.com>]

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@gmail.com> 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@gmail.com>
>> ---
>>  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@gmail.com>
>> + *
>> + * 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