[PATCH 1/3] pwm: ti: am33xx: Enable Auxiliary PWM using eCAP
Sukrut Bellary
sbellary at baylibre.com
Wed Mar 19 21:25:14 CET 2025
In am33xx SOC[1], enhanced capture (eCAP) supports auxiliary PWM (APWM).
This series adds the PWM driver support for the APWM feature for eCAP on
AM33xx.
eCAP HW also supports the capture mode. Currently, this driver only
supports APWM.
This is based on the Linux kernel driver -> drivers/pwm/pwm-tiecap.c
Version: v6.12
[1] AM335x TRM - https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf
[2] AM335x EVM - https://www.ti.com/tool/TMDXEVM3358
Signed-off-by: Sukrut Bellary <sbellary at baylibre.com>
---
drivers/pwm/Kconfig | 6 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-tiecap.c | 198 +++++++++++++++++++++++++++++++++++++++
3 files changed, 205 insertions(+)
create mode 100644 drivers/pwm/pwm-tiecap.c
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 6e79868d0efc..cbdc87bfccc6 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -118,3 +118,9 @@ config PWM_TI_EHRPWM
default y
help
PWM driver support for the EHRPWM controller found on TI SOCs.
+
+config PWM_TI_ECAP
+ bool "Enable support for ECAP PWM"
+ depends on DM_PWM && ARCH_OMAP2PLUS
+ help
+ PWM driver support for the ECAP controller found on TI SOCs.
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index e4d10c8dc3ef..5bd9837014da 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -24,3 +24,4 @@ obj-$(CONFIG_PWM_SIFIVE) += pwm-sifive.o
obj-$(CONFIG_PWM_TEGRA) += tegra_pwm.o
obj-$(CONFIG_PWM_SUNXI) += sunxi_pwm.o
obj-$(CONFIG_PWM_TI_EHRPWM) += pwm-ti-ehrpwm.o
+obj-$(CONFIG_PWM_TI_ECAP) += pwm-tiecap.o
diff --git a/drivers/pwm/pwm-tiecap.c b/drivers/pwm/pwm-tiecap.c
new file mode 100644
index 000000000000..13cf50aa2843
--- /dev/null
+++ b/drivers/pwm/pwm-tiecap.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * ECAP PWM driver
+ *
+ * Copyright (C) 2024 BayLibre, SAS
+ * Author: Sukrut Bellary <sbellary at baylibre.com>
+ */
+
+#include <clk.h>
+#include <div64.h>
+#include <dm.h>
+#include <dm/device_compat.h>
+#include <pwm.h>
+#include <asm/io.h>
+
+/* eCAP module registers */
+#define ECAP_PWM_CAP1 0x08
+#define ECAP_PWM_CAP2 0x0C
+#define ECAP_PWM_CAP3 0x10
+#define ECAP_PWM_CAP4 0x14
+
+#define ECAP_PWM_ECCTL2 0x2A
+#define ECAP_PWM_ECCTL2_APWM_POL_LOW BIT(10)
+#define ECAP_PWM_ECCTL2_APWM_MODE BIT(9)
+#define ECAP_PWM_ECCTL2_TSCTR_FREERUN BIT(4)
+#define ECAP_PWM_ECCTL2_SYNC_SEL_DISA (BIT(7) | BIT(6))
+
+#define NSEC_PER_SEC 1000000000L
+
+enum tiecap_pwm_polarity {
+ TIECAP_PWM_POLARITY_NORMAL,
+ TIECAP_PWM_POLARITY_INVERSED
+};
+
+enum tiecap_pwm_state {
+ TIECAP_APWM_DISABLED,
+ TIECAP_APWM_ENABLED
+};
+
+struct tiecap_pwm_priv {
+ fdt_addr_t regs;
+ u32 clk_rate;
+ enum tiecap_pwm_state pwm_state;
+};
+
+static int tiecap_pwm_set_config(struct udevice *dev, uint channel,
+ uint period_ns, uint duty_ns)
+{
+ struct tiecap_pwm_priv *priv = dev_get_priv(dev);
+ u32 period_cycles, duty_cycles;
+ unsigned long long c;
+ u16 value;
+
+ c = priv->clk_rate;
+ c = c * period_ns;
+ do_div(c, NSEC_PER_SEC);
+ period_cycles = (u32)c;
+
+ if (period_cycles < 1) {
+ period_cycles = 1;
+ duty_cycles = 1;
+ } else {
+ c = priv->clk_rate;
+ c = c * duty_ns;
+ do_div(c, NSEC_PER_SEC);
+ duty_cycles = (u32)c;
+ }
+
+ value = readw(priv->regs + ECAP_PWM_ECCTL2);
+
+ /* Configure APWM mode & disable sync option */
+ value |= ECAP_PWM_ECCTL2_APWM_MODE | ECAP_PWM_ECCTL2_SYNC_SEL_DISA;
+
+ writew(value, priv->regs + ECAP_PWM_ECCTL2);
+
+ if (priv->pwm_state == TIECAP_APWM_DISABLED) {
+ /* Update active registers */
+ writel(duty_cycles, priv->regs + ECAP_PWM_CAP2);
+ writel(period_cycles, priv->regs + ECAP_PWM_CAP1);
+ } else {
+ /* Update shadow registers to configure period and
+ * compare values. This helps current pwm period to
+ * complete on reconfiguring.
+ */
+ writel(duty_cycles, priv->regs + ECAP_PWM_CAP4);
+ writel(period_cycles, priv->regs + ECAP_PWM_CAP3);
+ }
+
+ return 0;
+}
+
+static int tiecap_pwm_set_enable(struct udevice *dev, uint channel, bool enable)
+{
+ struct tiecap_pwm_priv *priv = dev_get_priv(dev);
+ u16 value;
+
+ value = readw(priv->regs + ECAP_PWM_ECCTL2);
+
+ if (enable) {
+ /*
+ * Enable 'Free run Time stamp counter mode' to start counter
+ * and 'APWM mode' to enable APWM output
+ */
+ value |= ECAP_PWM_ECCTL2_TSCTR_FREERUN | ECAP_PWM_ECCTL2_APWM_MODE;
+ priv->pwm_state = TIECAP_APWM_ENABLED;
+ } else {
+ /* Disable 'Free run Time stamp counter mode' to stop counter
+ * and 'APWM mode' to put APWM output to low
+ */
+ value &= ~(ECAP_PWM_ECCTL2_TSCTR_FREERUN | ECAP_PWM_ECCTL2_APWM_MODE);
+ priv->pwm_state = TIECAP_APWM_DISABLED;
+ }
+
+ writew(value, priv->regs + ECAP_PWM_ECCTL2);
+
+ return 0;
+}
+
+static int tiecap_pwm_set_invert(struct udevice *dev, uint channel,
+ bool polarity)
+{
+ struct tiecap_pwm_priv *priv = dev_get_priv(dev);
+ u16 value;
+
+ value = readw(priv->regs + ECAP_PWM_ECCTL2);
+
+ if (polarity == TIECAP_PWM_POLARITY_INVERSED)
+ /* Duty cycle defines LOW period of PWM */
+ value |= ECAP_PWM_ECCTL2_APWM_POL_LOW;
+ else
+ /* Duty cycle defines HIGH period of PWM */
+ value &= ~ECAP_PWM_ECCTL2_APWM_POL_LOW;
+
+ writew(value, priv->regs + ECAP_PWM_ECCTL2);
+
+ return 0;
+}
+
+static int tiecap_pwm_of_to_plat(struct udevice *dev)
+{
+ struct tiecap_pwm_priv *priv = dev_get_priv(dev);
+
+ priv->regs = dev_read_addr(dev);
+ if (priv->regs == FDT_ADDR_T_NONE) {
+ dev_err(dev, "invalid address\n");
+ return -EINVAL;
+ }
+
+ dev_dbg(dev, "regs=0x%08lx\n", priv->regs);
+
+ return 0;
+}
+
+static int tiecap_pwm_probe(struct udevice *dev)
+{
+ struct tiecap_pwm_priv *priv = dev_get_priv(dev);
+ struct clk clk;
+ int err;
+
+ err = clk_get_by_name(dev, "fck", &clk);
+ if (err) {
+ dev_err(dev, "failed to get clock\n");
+ return err;
+ }
+
+ priv->clk_rate = clk_get_rate(&clk);
+ if (IS_ERR_VALUE(priv->clk_rate) || !priv->clk_rate) {
+ dev_err(dev, "failed to get clock rate\n");
+ if (IS_ERR_VALUE(priv->clk_rate))
+ return priv->clk_rate;
+
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static const struct pwm_ops tiecap_pwm_ops = {
+ .set_config = tiecap_pwm_set_config,
+ .set_enable = tiecap_pwm_set_enable,
+ .set_invert = tiecap_pwm_set_invert,
+};
+
+static const struct udevice_id tiecap_pwm_ids[] = {
+ { .compatible = "ti,am3352-ecap" },
+ { .compatible = "ti,am33xx-ecap" },
+ { }
+};
+
+U_BOOT_DRIVER(tiecap_pwm) = {
+ .name = "tiecap_pwm",
+ .id = UCLASS_PWM,
+ .of_match = tiecap_pwm_ids,
+ .ops = &tiecap_pwm_ops,
+ .probe = tiecap_pwm_probe,
+ .of_to_plat = tiecap_pwm_of_to_plat,
+ .priv_auto = sizeof(struct tiecap_pwm_priv),
+};
--
2.34.1
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