fpga: xilinx-spi: extract a common driver core

Factor out the gpio handshaking (using PROGRAM_B, INIT_B and DONE)
protocol in xilinx-core so that it can be reused for another driver.
This commit does not change anything functionally to xilinx-spi.

xilinx-core expects drivers to provide a write(const char* buf,
size_t count) function that performs the actual write to the device,
as well as a struct device* for resource management.

Signed-off-by: Charles Perry <charles.perry@savoirfairelinux.com>
Acked-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/20240321220447.3260065-2-charles.perry@savoirfairelinux.com
Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>

1 files changed, 15 insertions, 209 deletions

diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
index e1a227e7ff2a..8756504340de 100644
--- a/drivers/fpga/xilinx-spi.c
+++ b/drivers/fpga/xilinx-spi.c
@@ -10,127 +10,17 @@
  * the slave serial configuration interface.
  */
 
-#include <linux/delay.h>
-#include <linux/device.h>
-#include <linux/fpga/fpga-mgr.h>
-#include <linux/gpio/consumer.h>
+#include "xilinx-core.h"
+
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/of.h>
 #include <linux/spi/spi.h>
-#include <linux/sizes.h>
-
-struct xilinx_spi_conf {
-	struct spi_device *spi;
-	struct gpio_desc *prog_b;
-	struct gpio_desc *init_b;
-	struct gpio_desc *done;
-};
-
-static int get_done_gpio(struct fpga_manager *mgr)
-{
-	struct xilinx_spi_conf *conf = mgr->priv;
-	int ret;
-
-	ret = gpiod_get_value(conf->done);
-
-	if (ret < 0)
-		dev_err(&mgr->dev, "Error reading DONE (%d)\n", ret);
-
-	return ret;
-}
-
-static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
-{
-	if (!get_done_gpio(mgr))
-		return FPGA_MGR_STATE_RESET;
-
-	return FPGA_MGR_STATE_UNKNOWN;
-}
-
-/**
- * wait_for_init_b - wait for the INIT_B pin to have a given state, or wait
- * a given delay if the pin is unavailable
- *
- * @mgr:        The FPGA manager object
- * @value:      Value INIT_B to wait for (1 = asserted = low)
- * @alt_udelay: Delay to wait if the INIT_B GPIO is not available
- *
- * Returns 0 when the INIT_B GPIO reached the given state or -ETIMEDOUT if
- * too much time passed waiting for that. If no INIT_B GPIO is available
- * then always return 0.
- */
-static int wait_for_init_b(struct fpga_manager *mgr, int value,
-			   unsigned long alt_udelay)
-{
-	struct xilinx_spi_conf *conf = mgr->priv;
-	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
-
-	if (conf->init_b) {
-		while (time_before(jiffies, timeout)) {
-			int ret = gpiod_get_value(conf->init_b);
-
-			if (ret == value)
-				return 0;
-
-			if (ret < 0) {
-				dev_err(&mgr->dev, "Error reading INIT_B (%d)\n", ret);
-				return ret;
-			}
-
-			usleep_range(100, 400);
-		}
-
-		dev_err(&mgr->dev, "Timeout waiting for INIT_B to %s\n",
-			value ? "assert" : "deassert");
-		return -ETIMEDOUT;
-	}
-
-	udelay(alt_udelay);
-
-	return 0;
-}
-
-static int xilinx_spi_write_init(struct fpga_manager *mgr,
-				 struct fpga_image_info *info,
-				 const char *buf, size_t count)
-{
-	struct xilinx_spi_conf *conf = mgr->priv;
-	int err;
-
-	if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
-		dev_err(&mgr->dev, "Partial reconfiguration not supported\n");
-		return -EINVAL;
-	}
-
-	gpiod_set_value(conf->prog_b, 1);
-
-	err = wait_for_init_b(mgr, 1, 1); /* min is 500 ns */
-	if (err) {
-		gpiod_set_value(conf->prog_b, 0);
-		return err;
-	}
-
-	gpiod_set_value(conf->prog_b, 0);
-
-	err = wait_for_init_b(mgr, 0, 0);
-	if (err)
-		return err;
-
-	if (get_done_gpio(mgr)) {
-		dev_err(&mgr->dev, "Unexpected DONE pin state...\n");
-		return -EIO;
-	}
 
-	/* program latency */
-	usleep_range(7500, 7600);
-	return 0;
-}
-
-static int xilinx_spi_write(struct fpga_manager *mgr, const char *buf,
+static int xilinx_spi_write(struct xilinx_fpga_core *core, const char *buf,
 			    size_t count)
 {
-	struct xilinx_spi_conf *conf = mgr->priv;
+	struct spi_device *spi = to_spi_device(core->dev);
 	const char *fw_data = buf;
 	const char *fw_data_end = fw_data + count;
 
@@ -141,9 +31,9 @@ static int xilinx_spi_write(struct fpga_manager *mgr, const char *buf,
 		remaining = fw_data_end - fw_data;
 		stride = min_t(size_t, remaining, SZ_4K);
 
-		ret = spi_write(conf->spi, fw_data, stride);
+		ret = spi_write(spi, fw_data, stride);
 		if (ret) {
-			dev_err(&mgr->dev, "SPI error in firmware write: %d\n",
+			dev_err(core->dev, "SPI error in firmware write: %d\n",
 				ret);
 			return ret;
 		}
@@ -153,109 +43,25 @@ static int xilinx_spi_write(struct fpga_manager *mgr, const char *buf,
 	return 0;
 }
 
-static int xilinx_spi_apply_cclk_cycles(struct xilinx_spi_conf *conf)
-{
-	struct spi_device *spi = conf->spi;
-	const u8 din_data[1] = { 0xff };
-	int ret;
-
-	ret = spi_write(conf->spi, din_data, sizeof(din_data));
-	if (ret)
-		dev_err(&spi->dev, "applying CCLK cycles failed: %d\n", ret);
-
-	return ret;
-}
-
-static int xilinx_spi_write_complete(struct fpga_manager *mgr,
-				     struct fpga_image_info *info)
-{
-	struct xilinx_spi_conf *conf = mgr->priv;
-	unsigned long timeout = jiffies + usecs_to_jiffies(info->config_complete_timeout_us);
-	bool expired = false;
-	int done;
-	int ret;
-
-	/*
-	 * This loop is carefully written such that if the driver is
-	 * scheduled out for more than 'timeout', we still check for DONE
-	 * before giving up and we apply 8 extra CCLK cycles in all cases.
-	 */
-	while (!expired) {
-		expired = time_after(jiffies, timeout);
-
-		done = get_done_gpio(mgr);
-		if (done < 0)
-			return done;
-
-		ret = xilinx_spi_apply_cclk_cycles(conf);
-		if (ret)
-			return ret;
-
-		if (done)
-			return 0;
-	}
-
-	if (conf->init_b) {
-		ret = gpiod_get_value(conf->init_b);
-
-		if (ret < 0) {
-			dev_err(&mgr->dev, "Error reading INIT_B (%d)\n", ret);
-			return ret;
-		}
-
-		dev_err(&mgr->dev,
-			ret ? "CRC error or invalid device\n"
-			: "Missing sync word or incomplete bitstream\n");
-	} else {
-		dev_err(&mgr->dev, "Timeout after config data transfer\n");
-	}
-
-	return -ETIMEDOUT;
-}
-
-static const struct fpga_manager_ops xilinx_spi_ops = {
-	.state = xilinx_spi_state,
-	.write_init = xilinx_spi_write_init,
-	.write = xilinx_spi_write,
-	.write_complete = xilinx_spi_write_complete,
-};
-
 static int xilinx_spi_probe(struct spi_device *spi)
 {
-	struct xilinx_spi_conf *conf;
-	struct fpga_manager *mgr;
+	struct xilinx_fpga_core *core;
 
-	conf = devm_kzalloc(&spi->dev, sizeof(*conf), GFP_KERNEL);
-	if (!conf)
+	core = devm_kzalloc(&spi->dev, sizeof(*core), GFP_KERNEL);
+	if (!core)
 		return -ENOMEM;
 
-	conf->spi = spi;
+	core->dev = &spi->dev;
+	core->write = xilinx_spi_write;
 
-	/* PROGRAM_B is active low */
-	conf->prog_b = devm_gpiod_get(&spi->dev, "prog_b", GPIOD_OUT_LOW);
-	if (IS_ERR(conf->prog_b))
-		return dev_err_probe(&spi->dev, PTR_ERR(conf->prog_b),
-				     "Failed to get PROGRAM_B gpio\n");
-
-	conf->init_b = devm_gpiod_get_optional(&spi->dev, "init-b", GPIOD_IN);
-	if (IS_ERR(conf->init_b))
-		return dev_err_probe(&spi->dev, PTR_ERR(conf->init_b),
-				     "Failed to get INIT_B gpio\n");
-
-	conf->done = devm_gpiod_get(&spi->dev, "done", GPIOD_IN);
-	if (IS_ERR(conf->done))
-		return dev_err_probe(&spi->dev, PTR_ERR(conf->done),
-				     "Failed to get DONE gpio\n");
-
-	mgr = devm_fpga_mgr_register(&spi->dev,
-				     "Xilinx Slave Serial FPGA Manager",
-				     &xilinx_spi_ops, conf);
-	return PTR_ERR_OR_ZERO(mgr);
+	return xilinx_core_probe(core);
 }
 
 #ifdef CONFIG_OF
 static const struct of_device_id xlnx_spi_of_match[] = {
-	{ .compatible = "xlnx,fpga-slave-serial", },
+	{
+		.compatible = "xlnx,fpga-slave-serial",
+	},
 	{}
 };
 MODULE_DEVICE_TABLE(of, xlnx_spi_of_match);