by Charles Perry

[permalink] [raw]

Subject: Re: [PATCH 3/3] fpga: xilinx-selectmap: add new driver

On Feb 4, 2024, at 3:10 AM, Xu Yilun [email protected] wrote:
> On Wed, Jan 31, 2024 at 06:05:33PM -0500, Charles Perry wrote:
>> Xilinx 7 series FPGA can be programmed using a slave parallel port named
>> the SelectMAP interface in the datasheet. This slave interface is
>> compatible with the i.MX6 EIM bus controller but other types of external
>> memory mapped parallel bus might work.
>>
>> xilinx-selectmap currently only supports the x8 mode where data is loaded
>> at one byte per rising edge of the clock, with the MSb of each byte
>> presented to the D0 pin.
>>
>> Signed-off-by: Charles Perry <[email protected]>
>> ---
>> drivers/fpga/Kconfig | 8 +++
>> drivers/fpga/Makefile | 1 +
>> drivers/fpga/xilinx-core.c | 11 +++-
>> drivers/fpga/xilinx-core.h | 3 +-
>> drivers/fpga/xilinx-selectmap.c | 106 ++++++++++++++++++++++++++++++++
>> drivers/fpga/xilinx-spi.c | 3 +-
>> 6 files changed, 127 insertions(+), 5 deletions(-)
>> create mode 100644 drivers/fpga/xilinx-selectmap.c
>>
>> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
>> index d27a1ebf40838..37b35f58f0dfb 100644
>> --- a/drivers/fpga/Kconfig
>> +++ b/drivers/fpga/Kconfig
>> @@ -67,6 +67,14 @@ config FPGA_MGR_STRATIX10_SOC
>> config FPGA_MGR_XILINX_CORE
>> tristate
>>
>> +config FPGA_MGR_XILINX_SELECTMAP
>> + tristate "Xilinx Configuration over SelectMAP"
>> + depends on HAS_IOMEM
>> + select FPGA_MGR_XILINX_CORE
>> + help
>> + FPGA manager driver support for Xilinx FPGA configuration
>> + over SelectMAP interface.
>> +
>> config FPGA_MGR_XILINX_SPI
>> tristate "Xilinx Configuration over Slave Serial (SPI)"
>> depends on SPI
>> diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
>> index 7ec795b6a5a70..aeb89bb13517e 100644
>> --- a/drivers/fpga/Makefile
>> +++ b/drivers/fpga/Makefile
>> @@ -16,6 +16,7 @@ obj-$(CONFIG_FPGA_MGR_SOCFPGA_A10) += socfpga-a10.o
>> obj-$(CONFIG_FPGA_MGR_STRATIX10_SOC) += stratix10-soc.o
>> obj-$(CONFIG_FPGA_MGR_TS73XX) += ts73xx-fpga.o
>> obj-$(CONFIG_FPGA_MGR_XILINX_CORE) += xilinx-core.o
>> +obj-$(CONFIG_FPGA_MGR_XILINX_SELECTMAP) += xilinx-selectmap.o
>> obj-$(CONFIG_FPGA_MGR_XILINX_SPI) += xilinx-spi.o
>> obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA) += zynq-fpga.o
>> obj-$(CONFIG_FPGA_MGR_ZYNQMP_FPGA) += zynqmp-fpga.o
>> diff --git a/drivers/fpga/xilinx-core.c b/drivers/fpga/xilinx-core.c
>> index aff40e9394085..64117759be100 100644
>> --- a/drivers/fpga/xilinx-core.c
>> +++ b/drivers/fpga/xilinx-core.c
>> @@ -180,21 +180,26 @@ static const struct fpga_manager_ops xilinx_core_ops = {
>>
>> int xilinx_core_probe(struct xilinx_fpga_core *core, struct device *dev,
>> xilinx_write_func write,
>> - xilinx_write_one_dummy_byte_func write_one_dummy_byte)
>> + xilinx_write_one_dummy_byte_func write_one_dummy_byte,
>> + const char *prog_con_id, const char *init_con_id)
>
> These gpio name inputs are not necessary except for DTS format concern.
> Is it possible we don't change the names?
>

Krzysztof won't accept the old names as they are non standard (contain a
prohibited char "_" and use a "-b" prefix for active low). I agree that it
is cumbersome to have different gpio names injected in the core by the top
level driver.

Can I change the GPIO names of xlnx,fpga-slave-serial? i.e.:

* "prog_b" -> "prog"
* "init-b" -> "init"

and keep a fallback in the driver so that current users of this driver keep
working without adaptation in the DT.

>> {
>> struct fpga_manager *mgr;
>>
>> + if (!core || !dev || !write || !write_one_dummy_byte || !prog_con_id ||
>> + !init_con_id)
>> + return -EINVAL;
>
> These checks belong to Patch #1.
>

Ok

>> +
>> core->dev = dev;
>> core->write = write;
>> core->write_one_dummy_byte = write_one_dummy_byte;
>>
>> /* PROGRAM_B is active low */
>> - core->prog_b = devm_gpiod_get(dev, "prog_b", GPIOD_OUT_LOW);
>> + core->prog_b = devm_gpiod_get(dev, prog_con_id, GPIOD_OUT_LOW);
>> if (IS_ERR(core->prog_b))
>> return dev_err_probe(dev, PTR_ERR(core->prog_b),
>> "Failed to get PROGRAM_B gpio\n");
>>
>> - core->init_b = devm_gpiod_get_optional(dev, "init-b", GPIOD_IN);
>> + core->init_b = devm_gpiod_get_optional(dev, init_con_id, GPIOD_IN);
>> if (IS_ERR(core->init_b))
>> return dev_err_probe(dev, PTR_ERR(core->init_b),
>> "Failed to get INIT_B gpio\n");
>> diff --git a/drivers/fpga/xilinx-core.h b/drivers/fpga/xilinx-core.h
>> index 40e120945ba70..817f0e551d093 100644
>> --- a/drivers/fpga/xilinx-core.h
>> +++ b/drivers/fpga/xilinx-core.h
>> @@ -22,6 +22,7 @@ struct xilinx_fpga_core {
>>
>> int xilinx_core_probe(struct xilinx_fpga_core *core, struct device *dev,
>> xilinx_write_func write,
>> - xilinx_write_one_dummy_byte_func write_one_dummy_byte);
>> + xilinx_write_one_dummy_byte_func write_one_dummy_byte,
>> + const char *prog_con_id, const char *init_con_id);
>>
>> #endif /* __XILINX_CORE_H */
>> diff --git a/drivers/fpga/xilinx-selectmap.c b/drivers/fpga/xilinx-selectmap.c
>> new file mode 100644
>> index 0000000000000..08054e19bb498
>> --- /dev/null
>> +++ b/drivers/fpga/xilinx-selectmap.c
>> @@ -0,0 +1,106 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Xilinx Spartan6 and 7 Series SelectMAP interface driver
>> + *
>> + * (C) 2024 Charles Perry <[email protected]>
>> + *
>> + * Manage Xilinx FPGA firmware loaded over the SelectMAP configuration
>> + * interface.
>> + */
>> +
>> +#include "xilinx-core.h"
>> +
>> +#include <linux/platform_device.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/module.h>
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/of.h>
>> +#include <linux/io.h>
>> +
>> +struct xilinx_selectmap_conf {
>> + struct xilinx_fpga_core core;
>> + void __iomem *base;
>> + struct gpio_desc *csi_b;
>> + struct gpio_desc *rdwr_b;
>
> These 2 gpio_desc are not used globally, maybe remove them here.
>

Ok

>> +};
>> +
>> +#define to_xilinx_selectmap_conf(obj) \
>> + container_of(obj, struct xilinx_selectmap_conf, core)
>> +
>> +static int xilinx_selectmap_write(struct xilinx_fpga_core *core,
>> + const char *buf, size_t count)
>> +{
>> + struct xilinx_selectmap_conf *conf = to_xilinx_selectmap_conf(core);
>> + u32 i;
>> +
>> + for (i = 0; i < count; ++i)
>> + writeb(buf[i], conf->base);
>> +
>> + return 0;
>> +}
>> +
>> +static int xilinx_selectmap_apply_padding(struct xilinx_fpga_core *core)
>> +{
>> + struct xilinx_selectmap_conf *conf = to_xilinx_selectmap_conf(core);
>> +
>> + writeb(0xFF, conf->base);
>
> Seems only one callback needed. Just use write() to xfer 1 byte?
>
> Thanks,
> Yilun
>

Yes, will be changed.

Thank you,
Charles

>> + return 0;
>> +}
>> +
>> +static int xilinx_selectmap_probe(struct platform_device *pdev)
>> +{
>> + struct xilinx_selectmap_conf *conf;
>> + struct resource *r;
>> + void __iomem *base;
>> +
>> + conf = devm_kzalloc(&pdev->dev, sizeof(*conf), GFP_KERNEL);
>> + if (!conf)
>> + return -ENOMEM;
>> +
>> + base = devm_platform_get_and_ioremap_resource(pdev, 0, &r);
>> + if (IS_ERR(base))
>> + return dev_err_probe(&pdev->dev, PTR_ERR(base),
>> + "ioremap error\n");
>> + conf->base = base;
>> +
>> + /* CSI_B is active low */
>> + conf->csi_b =
>> + devm_gpiod_get_optional(&pdev->dev, "csi", GPIOD_OUT_HIGH);
>> + if (IS_ERR(conf->csi_b))
>> + return dev_err_probe(&pdev->dev, PTR_ERR(conf->csi_b),
>> + "Failed to get CSI_B gpio\n");
>> +
>> + /* RDWR_B is active low */
>> + conf->rdwr_b =
>> + devm_gpiod_get_optional(&pdev->dev, "rdwr", GPIOD_OUT_HIGH);
>> + if (IS_ERR(conf->rdwr_b))
>> + return dev_err_probe(&pdev->dev, PTR_ERR(conf->rdwr_b),
>> + "Failed to get RDWR_B gpio\n");
>> +
>> + return xilinx_core_probe(&conf->core, &pdev->dev,
>> + xilinx_selectmap_write,
>> + xilinx_selectmap_apply_padding, "prog",
>> + "init");
>> +}
>> +
>> +static const struct of_device_id xlnx_selectmap_of_match[] = {
>> + {
>> + .compatible = "xlnx,fpga-selectmap",
>> + },
>> + {}
>> +};
>> +MODULE_DEVICE_TABLE(of, xlnx_selectmap_of_match);
>> +
>> +static struct platform_driver xilinx_selectmap_driver = {
>> + .driver = {
>> + .name = "xilinx-selectmap",
>> + .of_match_table = xlnx_selectmap_of_match,
>> + },
>> + .probe = xilinx_selectmap_probe,
>> +};
>> +
>> +module_platform_driver(xilinx_selectmap_driver);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Charles Perry <[email protected]>");
>> +MODULE_DESCRIPTION("Load Xilinx FPGA firmware over SelectMap");
>> diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
>> index ec128dee97312..b9ab3d5da004c 100644
>> --- a/drivers/fpga/xilinx-spi.c
>> +++ b/drivers/fpga/xilinx-spi.c
>> @@ -74,7 +74,8 @@ static int xilinx_spi_probe(struct spi_device *spi)
>> conf->spi = spi;
>>
>> return xilinx_core_probe(&conf->core, &spi->dev, xilinx_spi_write,
>> - xilinx_spi_apply_cclk_cycles);
>> + xilinx_spi_apply_cclk_cycles, "prog_b",
>> + "init-b");
>> }
>>
>> #ifdef CONFIG_OF
>> --
>> 2.43.0
>>