[PATCH v3 1/1] timer: imx-gpt: Add timer support for i.MX SoCs family

[Jesse T]

I'm very sorry for my email issues I some how mess it up each time.

On Thu, Feb 11, 2021, 8:11 PM Jesse <mr.bossman075 at gmail.com> wrote:

> From: Jesse Taube <mr.bossman075 at gmail.com>
>
> This timer driver is using GPT Timer (General Purpose Timer)
> available on almost all i.MX SoCs family.
> Since this driver is only meant to provide u-boot's timer and counter,
> and most of the i.MX* SoCs use a 24Mhz crystal,
> let's only deal with that specific source.
>
> Signed-off-by: Giulio Benetti <giulio.benetti at benettiengineering.com>
> Signed-off-by: Jesse Taube <mr.bossman075 at gmail.com>
> ---
>  drivers/timer/Kconfig         |   7 ++
>  drivers/timer/Makefile        |   1 +
>  drivers/timer/imx-gpt-timer.c | 149 ++++++++++++++++++++++++++++++++++
>  3 files changed, 157 insertions(+)
>  create mode 100644 drivers/timer/imx-gpt-timer.c
>
> diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
> index 80743a2551..ee81dfa776 100644
> --- a/drivers/timer/Kconfig
> +++ b/drivers/timer/Kconfig
> @@ -227,4 +227,11 @@ config MCHP_PIT64B_TIMER
>           Select this to enable support for Microchip 64-bit periodic
>           interval timer.
>
> +config IMX_GPT_TIMER
> +       bool "NXP i.MX GPT timer support"
> +       depends on TIMER
> +       help
> +         Select this to enable support for the timer found on
> +         NXP i.MX devices.
> +
>  endmenu
> diff --git a/drivers/timer/Makefile b/drivers/timer/Makefile
> index eb5c48cc6c..e214ba7268 100644
> --- a/drivers/timer/Makefile
> +++ b/drivers/timer/Makefile
> @@ -25,3 +25,4 @@ obj-$(CONFIG_STM32_TIMER)     += stm32_timer.o
>  obj-$(CONFIG_X86_TSC_TIMER)    += tsc_timer.o
>  obj-$(CONFIG_MTK_TIMER)                += mtk_timer.o
>  obj-$(CONFIG_MCHP_PIT64B_TIMER)        += mchp-pit64b-timer.o
> +obj-$(CONFIG_IMX_GPT_TIMER)    += imx-gpt-timer.o
> diff --git a/drivers/timer/imx-gpt-timer.c b/drivers/timer/imx-gpt-timer.c
> new file mode 100644
> index 0000000000..62db6e663a
> --- /dev/null
> +++ b/drivers/timer/imx-gpt-timer.c
> @@ -0,0 +1,149 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2020
> + * Author(s): Giulio Benetti <giulio.benetti at benettiengineering.com>
> + */
> +
> +#include <common.h>
> +#include <clk.h>
> +#include <dm.h>
> +#include <fdtdec.h>
> +#include <timer.h>
> +#include <dm/device_compat.h>
> +
> +#include <asm/io.h>
> +
> +#define GPT_CR_SWR             0x00008000
> +#define GPT_CR_CLKSRC          0x000001C0
> +#define GPT_CR_EN_24M          0x00000400
> +#define GPT_CR_EN              0x00000001
> +#define GPT_PR_PRESCALER       0x00000FFF
> +#define GPT_PR_PRESCALER24M    0x0000F000
> +
> +#define NO_CLOCK               (0)
> +#define IPG_CLK                        (1 << 6)
> +#define IPG_CLK_HF             (2 << 6)
> +#define IPG_EXT                        (3 << 6)
> +#define IPG_CLK_32K            (4 << 6)
> +#define IPG_CLK_24M            (5 << 6)
> +
> +struct imx_gpt_timer_regs {
> +       u32 cr;
> +       u32 pr;
> +       u32 sr;
> +       u32 ir;
> +       u32 ocr1;
> +       u32 ocr2;
> +       u32 ocr3;
> +       u32 icr1;
> +       u32 icr2;
> +       u32 cnt;
> +};
> +
> +struct imx_gpt_timer_priv {
> +       struct imx_gpt_timer_regs *base;
> +};
> +
> +static u64 imx_gpt_timer_get_count(struct udevice *dev)
> +{
> +       struct imx_gpt_timer_priv *priv = dev_get_priv(dev);
> +       struct imx_gpt_timer_regs *regs = priv->base;
> +
> +       return readl(&regs->cnt);
> +}
> +
> +u32 imxrt_gpt_setup_ctrl(u32 rate)
> +{
> +       u32 ctlr = 0;
> +
> +       if (rate == 24000000UL) {
> +               ctlr |= IPG_CLK_24M;
> +               ctlr |= GPT_CR_EN_24M;
> +       } else {
> +               ctlr |= IPG_CLK;
> +       }
> +
> +       return ctlr;
> +}
> +
> +static int imx_gpt_timer_probe(struct udevice *dev)
> +{
> +       struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
> +       struct imx_gpt_timer_priv *priv = dev_get_priv(dev);
> +       struct imx_gpt_timer_regs *regs;
> +       struct clk clk;
> +       fdt_addr_t addr;
> +       u32 prescaler;
> +       u32 rate;
> +       u32 ctlr;
> +       int ret;
> +
> +       addr = dev_read_addr(dev);
> +       if (addr == FDT_ADDR_T_NONE)
> +               return -EINVAL;
> +
> +       priv->base = (struct imx_gpt_timer_regs *)addr;
> +
> +       ret = clk_get_by_index(dev, 0, &clk);
> +       if (ret < 0)
> +               return ret;
> +
> +       ret = clk_enable(&clk);
> +       if (ret) {
> +               dev_err(dev, "Failed to enable clock\n");
> +               return ret;
> +       }
> +
> +       regs = priv->base;
> +
> +       /* Reset the timer */
> +       setbits_le32(&regs->cr, GPT_CR_SWR);
> +
> +       /* Wait for timer to finish reset */
> +       while (readl(&regs->cr) & GPT_CR_SWR)
> +               ;
> +
> +       /* Get timer clock rate */
> +       rate = clk_get_rate(&clk);
> +       if (rate <= 0) {
> +               dev_err(dev, "Could not get clock rate...\n");
> +               return -EINVAL;
> +       }
> +
> +       /* Set timer frequency to 1MHz */
> +       uc_priv->clock_rate = CONFIG_SYS_HZ_CLOCK;
> +       prescaler = (rate / CONFIG_SYS_HZ_CLOCK) - 1;
> +
> +       if (prescaler > 0xfff) {
> +               dev_err(dev, "Could not set prescaler...\n");
> +               return -EINVAL;
> +       }
> +       /* We set timer prescaler to obtain a 1MHz timer counter frequency
> */
> +       writel(prescaler, &regs->pr);
> +
> +       ctlr = imxrt_gpt_setup_ctrl(rate);
> +
> +       /* Start timer */
> +       writel(ctlr, &regs->cr);
> +       setbits_le32(&regs->cr, GPT_CR_EN);
> +
> +       return 0;
> +}
> +
> +static const struct timer_ops imx_gpt_timer_ops = {
> +       .get_count = imx_gpt_timer_get_count,
> +};
> +
> +static const struct udevice_id imx_gpt_timer_ids[] = {
> +       { .compatible = "fsl,imxrt-gpt" },
> +       {}
> +};
> +
> +U_BOOT_DRIVER(imx_gpt_timer) = {
> +       .name = "imx_gpt_timer",
> +       .id = UCLASS_TIMER,
> +       .of_match = imx_gpt_timer_ids,
> +       .priv_auto = sizeof(struct imx_gpt_timer_priv),
> +       .probe = imx_gpt_timer_probe,
> +       .ops = &imx_gpt_timer_ops,
> +};
> --
> 2.30.0
>
>