Add a new driver for a generic PWM trigger for SPI offloads.
Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
---
v5 changes:
* Updated to accommodate changes in other patches in this series.
* Add MAINTAINERS entry.
v4 changes: new patch in v4
---
MAINTAINERS | 1 +
drivers/spi/Kconfig | 12 +++
drivers/spi/Makefile | 3 +
drivers/spi/spi-offload-trigger-pwm.c | 162 ++++++++++++++++++++++++++++++++++
4 files changed, 178 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index a43532a1edde..36a40aaa026a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22023,6 +22023,7 @@ SPI OFFLOAD
R: David Lechner <dlechner@xxxxxxxxxxxx>
F: Documentation/devicetree/bindings/spi/trigger-pwm.yaml
F: Documentation/devicetree/bindings/spi/trigger-source.yaml
+F: drivers/spi/spi-offload-trigger-pwm.c
F: drivers/spi/spi-offload.c
F: include/linux/spi/spi-offload.h
K: spi_offload
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index cdc483b0ec5c..867d4b55bef9 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -1308,4 +1308,16 @@ endif # SPI_SLAVE
config SPI_DYNAMIC
def_bool ACPI || OF_DYNAMIC || SPI_SLAVE
+if SPI_OFFLOAD
+
+comment "SPI Offload triggers"
+
+config SPI_OFFLOAD_TRIGGER_PWM
+ tristate "SPI offload trigger using PWM"
+ depends on PWM
+ help
+ Generic SPI offload trigger implemented using PWM output.
+
+endif # SPI_OFFLOAD
+
endif # SPI
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 39025ae5364d..9396d32e1994 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -163,3 +163,6 @@ obj-$(CONFIG_SPI_AMD) += spi-amd.o
# SPI slave protocol handlers
obj-$(CONFIG_SPI_SLAVE_TIME) += spi-slave-time.o
obj-$(CONFIG_SPI_SLAVE_SYSTEM_CONTROL) += spi-slave-system-control.o
+
+# SPI offload triggers
+obj-$(CONFIG_SPI_OFFLOAD_TRIGGER_PWM) += spi-offload-trigger-pwm.o
diff --git a/drivers/spi/spi-offload-trigger-pwm.c b/drivers/spi/spi-offload-trigger-pwm.c
new file mode 100644
index 000000000000..7e1b4a80becc
--- /dev/null
+++ b/drivers/spi/spi-offload-trigger-pwm.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024 Analog Devices Inc.
+ * Copyright (C) 2024 BayLibre, SAS
+ *
+ * Generic PWM trigger for SPI offload.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/mod_devicetable.h>
+#include <linux/spi/spi-offload.h>
+#include <linux/types.h>
+
+struct spi_offload_trigger_pwm_state {
+ struct device *dev;
+ struct pwm_device *pwm;
+};
+
+static bool spi_offload_trigger_pwm_match(struct spi_offload_trigger *trigger,
+ enum spi_offload_trigger_type type,
+ u64 *args, u32 nargs)
+{
+ if (nargs)
+ return false;
+
+ return type == SPI_OFFLOAD_TRIGGER_PERIODIC;
+}
+
+static int spi_offload_trigger_pwm_validate(struct spi_offload_trigger *trigger,
+ struct spi_offload_trigger_config *config)
+{
+ struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
+ struct spi_offload_trigger_periodic *periodic = &config->periodic;
+ struct pwm_waveform wf = { };
+ int ret;
+
+ if (config->type != SPI_OFFLOAD_TRIGGER_PERIODIC)
+ return -EINVAL;
+
+ if (!periodic->frequency_hz)
+ return -EINVAL;
+
+ wf.period_length_ns = DIV_ROUND_UP_ULL(NSEC_PER_SEC, periodic->frequency_hz);
+ /* REVISIT: 50% duty-cycle for now - may add config parameter later */
+ wf.duty_length_ns = wf.period_length_ns / 2;
+
+ ret = pwm_round_waveform_might_sleep(st->pwm, &wf);
+ if (ret < 0)
+ return ret;
+
+ periodic->frequency_hz = DIV_ROUND_UP_ULL(NSEC_PER_SEC, wf.period_length_ns);
+
+ return 0;
+}
+
+static int spi_offload_trigger_pwm_enable(struct spi_offload_trigger *trigger,
+ struct spi_offload_trigger_config *config)
+{
+ struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
+ struct spi_offload_trigger_periodic *periodic = &config->periodic;
+ struct pwm_waveform wf = { };
+
+ if (config->type != SPI_OFFLOAD_TRIGGER_PERIODIC)
+ return -EINVAL;
+
+ if (!periodic->frequency_hz)
+ return -EINVAL;
+
+ wf.period_length_ns = DIV_ROUND_UP_ULL(NSEC_PER_SEC, periodic->frequency_hz);
+ /* REVISIT: 50% duty-cycle for now - may add config parameter later */
+ wf.duty_length_ns = wf.period_length_ns / 2;
+
+ return pwm_set_waveform_might_sleep(st->pwm, &wf, false);
+}
+
+static void spi_offload_trigger_pwm_disable(struct spi_offload_trigger *trigger)
+{
+ struct spi_offload_trigger_pwm_state *st = spi_offload_trigger_get_priv(trigger);
+ struct pwm_waveform wf;
+ int ret;
+
+ ret = pwm_get_waveform_might_sleep(st->pwm, &wf);
+ if (ret < 0) {
+ dev_err(st->dev, "failed to get waveform: %d\n", ret);
+ return;
+ }
+
+ wf.duty_length_ns = 0;
+
+ ret = pwm_set_waveform_might_sleep(st->pwm, &wf, false);
+ if (ret < 0)
+ dev_err(st->dev, "failed to disable PWM: %d\n", ret);
+}
+
+static const struct spi_offload_trigger_ops spi_offload_trigger_pwm_ops = {
+ .match = spi_offload_trigger_pwm_match,
+ .validate = spi_offload_trigger_pwm_validate,
+ .enable = spi_offload_trigger_pwm_enable,
+ .disable = spi_offload_trigger_pwm_disable,
+};
+
+static void spi_offload_trigger_pwm_release(void *data)
+{
+ pwm_disable(data);
+}
+
+static int spi_offload_trigger_pwm_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct spi_offload_trigger_info info = {
+ .fwnode = dev_fwnode(dev),
+ .ops = &spi_offload_trigger_pwm_ops,
+ };
+ struct spi_offload_trigger_pwm_state *st;
+ struct pwm_state state;
+ int ret;
+
+ st = devm_kzalloc(&pdev->dev, sizeof(*st), GFP_KERNEL);
+ if (!st)
+ return -ENOMEM;
+
+ info.priv = st;
+ st->dev = dev;
+
+ st->pwm = devm_pwm_get(&pdev->dev, NULL);
+ if (IS_ERR(st->pwm))
+ return dev_err_probe(dev, PTR_ERR(st->pwm), "failed to get PWM\n");
+
+ /* init with duty_cycle = 0, output enabled to ensure trigger off */
+ pwm_init_state(st->pwm, &state);
+ state.enabled = true;
+
+ ret = pwm_apply_might_sleep(st->pwm, &state);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "failed to apply PWM state\n");
+
+ ret = devm_add_action_or_reset(dev, spi_offload_trigger_pwm_release, st->pwm);
+ if (ret)
+ return ret;
+
+ return devm_spi_offload_trigger_register(dev, &info);
+}
+
+static const struct of_device_id spi_offload_trigger_pwm_of_match_table[] = {
+ { .compatible = "trigger-pwm" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, spi_offload_trigger_pwm_of_match_table);
+
+static struct platform_driver spi_offload_trigger_pwm_driver = {
+ .driver = {
+ .name = "trigger-pwm",
+ .of_match_table = spi_offload_trigger_pwm_of_match_table,
+ },
+ .probe = spi_offload_trigger_pwm_probe,
+};
+module_platform_driver(spi_offload_trigger_pwm_driver);
+
+MODULE_AUTHOR("David Lechner <dlechner@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Generic PWM trigger");
+MODULE_LICENSE("GPL");
--
2.43.0
