[PATCH 1/3] pwm: Add PWM driver for SAMA5D2
Dan Sneddon
dan.sneddon at microchip.com
Tue Sep 21 01:28:44 CEST 2021
Add support for the PWM found on the SAMA5D2 family of devices.
Signed-off-by: Dan Sneddon <dan.sneddon at microchip.com>
---
drivers/pwm/Kconfig | 6 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-at91.c | 207 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 214 insertions(+)
create mode 100644 drivers/pwm/pwm-at91.c
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index cf7f4c6840..691bbcd469 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -91,3 +91,9 @@ config PWM_TI_EHRPWM
default y
help
PWM driver support for the EHRPWM controller found on TI SOCs.
+
+config PWM_AT91
+ bool "Enable support for PWM found on AT91 SoC's"
+ depends on DM_PWM && ARCH_AT91
+ help
+ Support for PWM hardware on AT91 based SoC.
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 10d244bfb7..6cdcbdb996 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -21,3 +21,4 @@ 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_AT91) += pwm-at91.o
diff --git a/drivers/pwm/pwm-at91.c b/drivers/pwm/pwm-at91.c
new file mode 100644
index 0000000000..95597aee55
--- /dev/null
+++ b/drivers/pwm/pwm-at91.c
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * PWM support for Microchip AT91 architectures.
+ *
+ * Copyright (C) 2021 Microchip Technology Inc. and its subsidiaries
+ *
+ * Author: Dan Sneddon <daniel.sneddon at microchip.com>
+ *
+ * Based on drivers/pwm/pwm-atmel.c from Linux.
+ */
+#include <clk.h>
+#include <common.h>
+#include <div64.h>
+#include <dm.h>
+#include <linux/bitops.h>
+#include <linux/io.h>
+#include <pwm.h>
+
+#define PERIOD_BITS 16
+#define PWM_MAX_PRES 10
+#define NSEC_PER_SEC 1000000000L
+
+#define PWM_ENA 0x04
+#define PWM_CHANNEL_OFFSET 0x20
+#define PWM_CMR 0x200
+#define PWM_CMR_CPRE_MSK GENMASK(3, 0)
+#define PWM_CMR_CPOL BIT(9)
+#define PWM_CDTY 0x204
+#define PWM_CPRD 0x20C
+
+struct at91_pwm_priv {
+ void __iomem *base;
+ struct clk pclk;
+ u32 clkrate;
+};
+
+static int at91_pwm_calculate_cprd_and_pres(struct udevice *dev,
+ unsigned long clkrate,
+ uint period_ns, uint duty_ns,
+ unsigned long *cprd, u32 *pres)
+{
+ u64 cycles = period_ns;
+ int shift;
+
+ /* Calculate the period cycles and prescale value */
+ cycles *= clkrate;
+ do_div(cycles, NSEC_PER_SEC);
+
+ /*
+ * The register for the period length is period_bits bits wide.
+ * So for each bit the number of clock cycles is wider divide the input
+ * clock frequency by two using pres and shift cprd accordingly.
+ */
+ shift = fls(cycles) - PERIOD_BITS;
+
+ if (shift > PWM_MAX_PRES) {
+ return -EINVAL;
+ } else if (shift > 0) {
+ *pres = shift;
+ cycles >>= *pres;
+ } else {
+ *pres = 0;
+ }
+
+ *cprd = cycles;
+
+ return 0;
+}
+
+static void at91_pwm_calculate_cdty(uint period_ns, uint duty_ns,
+ unsigned long clkrate, unsigned long cprd,
+ u32 pres, unsigned long *cdty)
+{
+ u64 cycles = duty_ns;
+
+ cycles *= clkrate;
+ do_div(cycles, NSEC_PER_SEC);
+ cycles >>= pres;
+ *cdty = cprd - cycles;
+}
+
+/**
+ * Returns: channel status after set operation
+ */
+static bool at91_pwm_set(void __iomem *base, uint channel, bool enable)
+{
+ u32 val, cur_status;
+
+ val = ioread32(base + PWM_ENA);
+ cur_status = !!(val & BIT(channel));
+
+ /* if channel is already in that state, do nothing */
+ if (!(enable ^ cur_status))
+ return cur_status;
+
+ if (enable)
+ val |= BIT(channel);
+ else
+ val &= ~(BIT(channel));
+
+ iowrite32(val, base + PWM_ENA);
+
+ return cur_status;
+}
+
+static int at91_pwm_set_enable(struct udevice *dev, uint channel, bool enable)
+{
+ struct at91_pwm_priv *priv = dev_get_priv(dev);
+
+ at91_pwm_set(priv->base, channel, enable);
+
+ return 0;
+}
+
+static int at91_pwm_set_config(struct udevice *dev, uint channel,
+ uint period_ns, uint duty_ns)
+{
+ struct at91_pwm_priv *priv = dev_get_priv(dev);
+ unsigned long cprd, cdty;
+ u32 pres, val;
+ int channel_enabled;
+ int ret;
+
+ ret = at91_pwm_calculate_cprd_and_pres(dev, priv->clkrate, period_ns,
+ duty_ns, &cprd, &pres);
+ if (ret)
+ return ret;
+
+ at91_pwm_calculate_cdty(period_ns, duty_ns, priv->clkrate, cprd, pres, &cdty);
+
+ /* disable the channel */
+ channel_enabled = at91_pwm_set(priv->base, channel, false);
+
+ /* It is necessary to preserve CPOL, inside CMR */
+ val = ioread32(priv->base + (channel * PWM_CHANNEL_OFFSET) + PWM_CMR);
+ val = (val & ~PWM_CMR_CPRE_MSK) | (pres & PWM_CMR_CPRE_MSK);
+ iowrite32(val, priv->base + (channel * PWM_CHANNEL_OFFSET) + PWM_CMR);
+
+ iowrite32(cprd, priv->base + (channel * PWM_CHANNEL_OFFSET) + PWM_CPRD);
+
+ iowrite32(cdty, priv->base + (channel * PWM_CHANNEL_OFFSET) + PWM_CDTY);
+
+ /* renable the channel if needed */
+ if (channel_enabled)
+ at91_pwm_set(priv->base, channel, true);
+
+ return 0;
+}
+
+static int at91_pwm_set_invert(struct udevice *dev, uint channel,
+ bool polarity)
+{
+ struct at91_pwm_priv *priv = dev_get_priv(dev);
+ u32 val;
+
+ val = ioread32(priv->base + (channel * PWM_CHANNEL_OFFSET) + PWM_CMR);
+ if (polarity)
+ val |= PWM_CMR_CPOL;
+ else
+ val &= ~PWM_CMR_CPOL;
+ iowrite32(val, priv->base + (channel * PWM_CHANNEL_OFFSET) + PWM_CMR);
+
+ return 0;
+}
+
+static int at91_pwm_probe(struct udevice *dev)
+{
+ struct at91_pwm_priv *priv = dev_get_priv(dev);
+ int ret;
+
+ priv->base = dev_read_addr_ptr(dev);
+ if (!priv->base)
+ return -EINVAL;
+
+ ret = clk_get_by_index(dev, 0, &priv->pclk);
+ if (ret)
+ return ret;
+
+ /* clocks aren't ref-counted so just enabled them once here */
+ ret = clk_enable(&priv->pclk);
+ if (ret)
+ return ret;
+
+ priv->clkrate = clk_get_rate(&priv->pclk);
+
+ return ret;
+}
+
+static const struct pwm_ops at91_pwm_ops = {
+ .set_config = at91_pwm_set_config,
+ .set_enable = at91_pwm_set_enable,
+ .set_invert = at91_pwm_set_invert,
+};
+
+static const struct udevice_id at91_pwm_of_match[] = {
+ { .compatible = "atmel,sama5d2-pwm" },
+ { }
+};
+
+U_BOOT_DRIVER(at91_pwm) = {
+ .name = "at91_pwm",
+ .id = UCLASS_PWM,
+ .of_match = at91_pwm_of_match,
+ .probe = at91_pwm_probe,
+ .priv_auto = sizeof(struct at91_pwm_priv),
+ .ops = &at91_pwm_ops,
+};
--
2.17.1
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