-----Original Message----- From: Heiko Schocher hs@denx.de Sent: 15 April 2020 22:34 To: Yash Shah yash.shah@sifive.com Cc: martyn.welch@collabora.co.uk; u-boot@lists.denx.de Subject: Re: [PATCH] pwm: Add PWM driver for SiFive SoC
[External Email] Do not click links or attachments unless you recognize the sender and know the content is safe
Hello Yash Shah,
Am 15.04.2020 um 08:32 schrieb Yash Shah:
Adds a PWM driver for PWM chip present in SiFive's HiFive Unleashed SoC This driver is simple port of Linux pwm sifive driver.
So please add more information from exatly which linux version this patch is from, see:
https://www.denx.de/wiki/U- Boot/Patches#Attributing_Code_Copyrights_Sign
Sure, will refer this doc and send a v2 accordingly.
Signed-off-by: Yash Shah yash.shah@sifive.com
drivers/pwm/Kconfig | 6 ++ drivers/pwm/Makefile | 1 + drivers/pwm/pwm-sifive.c | 181
+++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 188 insertions(+) create mode 100644 drivers/pwm/pwm-sifive.c
You introduce a new devicetree node, please add a documentation in doc/device-tree-bindings/pwm/
Will add the dt documentation.
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 1f36fc7..d6ea9ee 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -40,6 +40,12 @@ config PWM_SANDBOX useful. The PWM can be enabled but is not connected to any outputs so this is not very useful.
+config PWM_SIFIVE
bool "Enable support for SiFive PWM"depends on DM_PWMhelpThis PWM is found SiFive's FU540 and other SoCs.- config PWM_TEGRA bool "Enable support for the Tegra PWM" depends on DM_PWM
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index a837c35..e2d4185 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -12,6 +12,7 @@ obj-$(CONFIG_DM_PWM) += pwm-uclass.o
obj-$(CONFIG_PWM_EXYNOS) += exynos_pwm.o obj-$(CONFIG_PWM_IMX) += pwm-imx.o pwm-imx-util.o +obj-$(CONFIG_PWM_SIFIVE) += pwm-sifive.o
Please keep this list sorted.
Sure. My bad.
obj-$(CONFIG_PWM_ROCKCHIP) += rk_pwm.o obj-$(CONFIG_PWM_SANDBOX) += sandbox_pwm.o obj-$(CONFIG_PWM_TEGRA) += tegra_pwm.o diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c new file mode 100644 index 0000000..c54297e --- /dev/null +++ b/drivers/pwm/pwm-sifive.c @@ -0,0 +1,181 @@ +// SPDX-License-Identifier: GPL-2.0+ +/*
- Copyright (C) 2020 SiFive, Inc
- For SiFive's PWM IP block documentation please refer Chapter 14 of
- Reference Manual :
+https://static.dev.sifive.com/FU540-C000-v1.0.pdf
- Limitations:
- When changing both duty cycle and period, we cannot prevent in
- software that the output might produce a period with mixed
- settings (new period length and old duty cycle).
- The hardware cannot generate a 100% duty cycle.
- The hardware generates only inverted output.
- */
+#include <common.h> +#include <clk.h> +#include <div64.h> +#include <dm.h> +#include <pwm.h> +#include <regmap.h> +#include <linux/io.h> +#include <linux/log2.h> +#include <linux/bitfield.h>
+/* PWMCFG fields */ +#define PWM_SIFIVE_PWMCFG_SCALE GENMASK(3, 0) +#define PWM_SIFIVE_PWMCFG_STICKY BIT(8) +#define PWM_SIFIVE_PWMCFG_ZERO_CMP BIT(9) +#define PWM_SIFIVE_PWMCFG_DEGLITCH BIT(10) +#define PWM_SIFIVE_PWMCFG_EN_ALWAYS BIT(12) +#define PWM_SIFIVE_PWMCFG_EN_ONCE BIT(13) +#define PWM_SIFIVE_PWMCFG_CENTER BIT(16) +#define PWM_SIFIVE_PWMCFG_GANG BIT(24) +#define PWM_SIFIVE_PWMCFG_IP BIT(28)
+/* PWM_SIFIVE_SIZE_PWMCMP is used to calculate offset for pwmcmpX
registers */
+#define PWM_SIFIVE_SIZE_PWMCMP 4 +#define PWM_SIFIVE_CMPWIDTH 16
+DECLARE_GLOBAL_DATA_PTR;
+struct pwm_sifive_regs {
unsigned long cfg;unsigned long cnt;unsigned long pwms;unsigned long cmp0;+};
+struct pwm_sifive_data {
struct pwm_sifive_regs regs;+};
+struct pwm_sifive_priv {
fdt_addr_t base;ulong freq;const struct pwm_sifive_data *data; };+static int pwm_sifive_set_invert(struct udevice *dev, uint channel,
bool polarity) {debug("%s: Do not support polarity\n", __func__);return 0;+}
You don;t need this function.
+static int pwm_sifive_set_config(struct udevice *dev, uint channel,
uint period_ns, uint duty_ns) {struct pwm_sifive_priv *priv = dev_get_priv(dev);const struct pwm_sifive_regs *regs = &priv->data->regs;unsigned long scale_pow;unsigned long long num;u32 scale, val = 0, frac;debug("%s: period_ns=%u, duty_ns=%u\n", __func__, period_ns,- duty_ns);
/** The PWM unit is used with pwmzerocmp=0, so the only way tomodify the
* period length is using pwmscale which provides the number of bitsthe
* counter is shifted before being feed to the comparators. A period* lasts (1 << (PWM_SIFIVE_CMPWIDTH + pwmscale)) clock ticks.* (1 << (PWM_SIFIVE_CMPWIDTH + scale)) * 10^9/rate = period*/scale_pow = lldiv((uint64_t)priv->freq * period_ns, 1000000000);scale = clamp(ilog2(scale_pow) - PWM_SIFIVE_CMPWIDTH, 0, 0xf);val |= FIELD_PREP(PWM_SIFIVE_PWMCFG_SCALE, scale);/** The problem of output producing mixed setting as mentioned at top,* occurs here. To minimize the window for this problem, we are* calculating the register values first and then writing them* consecutively*/num = (u64)duty_ns * (1U << PWM_SIFIVE_CMPWIDTH);frac = DIV_ROUND_CLOSEST_ULL(num, period_ns);frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);writel(val, (void __iomem *)priv->base + regs->cfg);Do you really need this cast on each readl/writel call?
Will fix this in v2. Thanks for your comments.
- Yash