Message-ID: <290bd079-5627-60b0-a177-ad5608ce1211@amlogic.com>
Date:   Thu, 30 Dec 2021 17:35:33 +0800
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Subject: Re: [PATCH V2 4/6] tty: serial: meson: The UART baud rate calculation
 is described using the common clock code. Also added S4 chip uart Compatible.
Content-Language: en-US
To:     Vyacheslav <adeep@lexina.in>, <linux-serial@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-amlogic@lists.infradead.org>, <linux-kernel@vger.kernel.org>
CC:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Kevin Hilman <khilman@baylibre.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>
References: <20211229135350.9659-1-yu.tu@amlogic.com>
 <20211229135350.9659-5-yu.tu@amlogic.com>
 <fca61771-3b0d-d306-39bf-7b271dc148d9@lexina.in>
From:   Yu Tu <yu.tu@amlogic.com>
In-Reply-To: <fca61771-3b0d-d306-39bf-7b271dc148d9@lexina.in>
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Precedence: bulk

Hi Vyacheslav,
	Thank you very much for your reply.

On 2021/12/30 3:07, Vyacheslav wrote:
> [ EXTERNAL EMAIL ]
> 
> 
> 
> 29.12.2021 16:53, Yu Tu пишет:
>> Using the common Clock code to describe the UART baud rate clock makes
>> it easier for the UART driver to be compatible with the baud rate
>> requirements of the UART IP on different meson chips
>>
>> Signed-off-by: Yu Tu <yu.tu@amlogic.com>
>> ---
>>   drivers/tty/serial/Kconfig      |   1 +
>>   drivers/tty/serial/meson_uart.c | 303 ++++++++++++++++++++++++++------
>>   2 files changed, 249 insertions(+), 55 deletions(-)
>>
>> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
>> index 780908d43557..32e238173036 100644
>> --- a/drivers/tty/serial/Kconfig
>> +++ b/drivers/tty/serial/Kconfig
>> @@ -198,6 +198,7 @@ config SERIAL_KGDB_NMI
>>   config SERIAL_MESON
>>       tristate "Meson serial port support"
>>       depends on ARCH_MESON
>> +    depends on COMMON_CLK
>>       select SERIAL_CORE
>>       help
>>         This enables the driver for the on-chip UARTs of the Amlogic
>> diff --git a/drivers/tty/serial/meson_uart.c 
>> b/drivers/tty/serial/meson_uart.c
>> index 99efe62a1507..9b07e3534969 100644
>> --- a/drivers/tty/serial/meson_uart.c
>> +++ b/drivers/tty/serial/meson_uart.c
>> @@ -6,6 +6,7 @@
>>    */
>>   #include <linux/clk.h>
>> +#include <linux/clk-provider.h>
>>   #include <linux/console.h>
>>   #include <linux/delay.h>
>>   #include <linux/init.h>
>> @@ -65,9 +66,7 @@
>>   #define AML_UART_RECV_IRQ(c)        ((c) & 0xff)
>>   /* AML_UART_REG5 bits */
>> -#define AML_UART_BAUD_MASK        0x7fffff
>>   #define AML_UART_BAUD_USE        BIT(23)
>> -#define AML_UART_BAUD_XTAL        BIT(24)
>>   #define AML_UART_PORT_NUM        12
>>   #define AML_UART_PORT_OFFSET        6
>> @@ -76,6 +75,21 @@
>>   #define AML_UART_POLL_USEC        5
>>   #define AML_UART_TIMEOUT_USEC        10000
>> +struct meson_uart_data {
>> +    struct uart_port    port;
>> +    struct clk        *pclk;
>> +    struct clk        *baud_clk;
>> +    struct clk_divider    baud_div;
>> +    struct clk_mux        use_xtal_mux;
>> +    struct clk_mux        xtal_clk_sel_mux;
>> +    struct clk_mux        xtal2_clk_sel_mux;
>> +    struct clk_fixed_factor    xtal_div2;
>> +    struct clk_fixed_factor    xtal_div3;
>> +    struct clk_fixed_factor    clk81_div4;
>> +    bool            no_clk81_input;
>> +    bool            has_xtal_clk_sel;
>> +};
>> +
>>   static struct uart_driver meson_uart_driver;
>>   static struct uart_port *meson_ports[AML_UART_PORT_NUM];
>> @@ -270,14 +284,11 @@ static void meson_uart_reset(struct uart_port 
>> *port)
>>   static int meson_uart_startup(struct uart_port *port)
>>   {
>>       u32 val;
>> -    int ret = 0;
>> +    int ret;
>> -    val = readl(port->membase + AML_UART_CONTROL);
>> -    val |= AML_UART_CLEAR_ERR;
>> -    writel(val, port->membase + AML_UART_CONTROL);
>> -    val &= ~AML_UART_CLEAR_ERR;
>> -    writel(val, port->membase + AML_UART_CONTROL);
>> +    meson_uart_reset(port);
>> +    val = readl(port->membase + AML_UART_CONTROL);
>>       val |= (AML_UART_RX_EN | AML_UART_TX_EN);
>>       writel(val, port->membase + AML_UART_CONTROL);
>> @@ -295,19 +306,17 @@ static int meson_uart_startup(struct uart_port 
>> *port)
>>   static void meson_uart_change_speed(struct uart_port *port, unsigned 
>> long baud)
>>   {
>> +    struct meson_uart_data *private_data = port->private_data;
>>       u32 val;
>>       while (!meson_uart_tx_empty(port))
>>           cpu_relax();
>> -    if (port->uartclk == 24000000) {
>> -        val = ((port->uartclk / 3) / baud) - 1;
>> -        val |= AML_UART_BAUD_XTAL;
>> -    } else {
>> -        val = ((port->uartclk * 10 / (baud * 4) + 5) / 10) - 1;
>> -    }
>> +    val = readl(port->membase + AML_UART_REG5);
>>       val |= AML_UART_BAUD_USE;
>>       writel(val, port->membase + AML_UART_REG5);
>> +
>> +    clk_set_rate(private_data->baud_clk, baud);
>>   }
>>   static void meson_uart_set_termios(struct uart_port *port,
>> @@ -397,11 +406,27 @@ static int meson_uart_verify_port(struct 
>> uart_port *port,
>>   static void meson_uart_release_port(struct uart_port *port)
>>   {
>> -    /* nothing to do */
>> +    struct meson_uart_data *private_data = port->private_data;
>> +
>> +    clk_disable_unprepare(private_data->baud_clk);
>> +    clk_disable_unprepare(private_data->pclk);
>>   }
>>   static int meson_uart_request_port(struct uart_port *port)
>>   {
>> +    struct meson_uart_data *private_data = port->private_data;
>> +    int ret;
>> +
>> +    ret = clk_prepare_enable(private_data->pclk);
>> +    if (ret)
>> +        return ret;
>> +
>> +    ret = clk_prepare_enable(private_data->baud_clk);
>> +    if (ret) {
>> +        clk_disable_unprepare(private_data->pclk);
>> +        return ret;
>> +    }
>> +
>>       return 0;
>>   }
>> @@ -629,56 +654,175 @@ static struct uart_driver meson_uart_driver = {
>>       .cons        = MESON_SERIAL_CONSOLE,
>>   };
>> -static inline struct clk *meson_uart_probe_clock(struct device *dev,
>> -                         const char *id)
>> +static int meson_uart_register_clk(struct uart_port *port,
>> +                   const char *name_suffix,
>> +                   const struct clk_parent_data *parent_data,
>> +                   unsigned int num_parents,
>> +                   const struct clk_ops *ops,
>> +                   struct clk_hw *hw)
>>   {
>> -    struct clk *clk = NULL;
>> +    struct clk_init_data init = { };
>> +    char clk_name[32];
>>       int ret;
>> -    clk = devm_clk_get(dev, id);
>> -    if (IS_ERR(clk))
>> -        return clk;
>> +    snprintf(clk_name, sizeof(clk_name), "%s#%s", dev_name(port->dev),
>> +         name_suffix);
>> -    ret = clk_prepare_enable(clk);
>> -    if (ret) {
>> -        dev_err(dev, "couldn't enable clk\n");
>> -        return ERR_PTR(ret);
>> -    }
>> +    init.name = clk_name;
>> +    init.ops = ops;
>> +    init.flags = CLK_SET_RATE_PARENT;
>> +    init.parent_data = parent_data;
>> +    init.num_parents = num_parents;
>> +
>> +    hw->init = &init;
>> -    devm_add_action_or_reset(dev,
>> -            (void(*)(void *))clk_disable_unprepare,
>> -            clk);
>> +    ret = devm_clk_hw_register(port->dev, hw);
>> +    if (ret)
>> +        return dev_err_probe(port->dev, ret,
>> +                     "Failed to register the '%s' clock\n",
>> +                     clk_name);
>> -    return clk;
>> +    return ret;
>>   }
>> -static int meson_uart_probe_clocks(struct platform_device *pdev,
>> -                   struct uart_port *port)
>> -{
>> -    struct clk *clk_xtal = NULL;
>> -    struct clk *clk_pclk = NULL;
>> -    struct clk *clk_baud = NULL;
>> +static int meson_uart_probe_clocks(struct uart_port *port,
>> +                   bool register_clk81_div4)
>> +{
>> +    struct meson_uart_data *private_data = port->private_data;
>> +    struct clk_parent_data use_xtal_mux_parents[2] = {
>> +        { .index = -1, },
>> +        { .index = -1, },
>> +    };
>> +    struct clk_parent_data xtal_clk_sel_mux_parents[2] = { };
>> +    struct clk_parent_data xtal2_clk_sel_mux_parents[2] = { };
>> +    struct clk_parent_data xtal_div_parent = { .fw_name = "xtal", };
>> +    struct clk_parent_data clk81_div_parent = { .fw_name = "baud", };
>> +    struct clk_parent_data baud_div_parent = { };
>> +    struct clk *clk_baud, *clk_xtal;
>> +    int ret;
>> -    clk_pclk = meson_uart_probe_clock(&pdev->dev, "pclk");
>> -    if (IS_ERR(clk_pclk))
>> -        return PTR_ERR(clk_pclk);
>> +    private_data->pclk = devm_clk_get(port->dev, "pclk");
>> +    if (IS_ERR(private_data->pclk))
>> +        return dev_err_probe(port->dev, PTR_ERR(private_data->pclk),
>> +                     "Failed to get the 'pclk' clock\n");
>> +
>> +    clk_baud = devm_clk_get(port->dev, "baud");
>> +    if (IS_ERR(clk_baud))
>> +        return dev_err_probe(port->dev, PTR_ERR(clk_baud),
>> +                     "Failed to get the 'baud' clock\n");
>> -    clk_xtal = meson_uart_probe_clock(&pdev->dev, "xtal");
>> +    clk_xtal = devm_clk_get(port->dev, "xtal");
>>       if (IS_ERR(clk_xtal))
>> -        return PTR_ERR(clk_xtal);
>> +        return dev_err_probe(port->dev, PTR_ERR(clk_xtal),
>> +                     "Failed to get the 'xtal' clock\n");
>> +
>> +    private_data->xtal_div3.mult = 1;
>> +    private_data->xtal_div3.div = 3;
>> +    ret = meson_uart_register_clk(port, "xtal_div3", &xtal_div_parent,
>> +                      1, &clk_fixed_factor_ops,
>> +                      &private_data->xtal_div3.hw);
>> +    if (ret)
>> +        return ret;
>> -    clk_baud = meson_uart_probe_clock(&pdev->dev, "baud");
>> -    if (IS_ERR(clk_baud))
>> -        return PTR_ERR(clk_baud);
>> +    if (register_clk81_div4) {
>> +        private_data->clk81_div4.mult = 1;
>> +        private_data->clk81_div4.div = 4;
>> +        ret = meson_uart_register_clk(port, "clk81_div4",
>> +                          &clk81_div_parent, 1,
>> +                          &clk_fixed_factor_ops,
>> +                          &private_data->clk81_div4.hw);
>> +        if (ret)
>> +            return ret;
>> +
>> +        use_xtal_mux_parents[0].hw = &private_data->clk81_div4.hw;
>> +    }
>> -    port->uartclk = clk_get_rate(clk_baud);
>> +    if (private_data->has_xtal_clk_sel) {
>> +        private_data->xtal_div2.mult = 1;
>> +        private_data->xtal_div2.div = 2;
>> +        ret = meson_uart_register_clk(port, "xtal_div2",
>> +                          &xtal_div_parent, 1,
>> +                          &clk_fixed_factor_ops,
>> +                          &private_data->xtal_div2.hw);
>> +        if (ret)
>> +            return ret;
>> +
>> +        xtal_clk_sel_mux_parents[0].hw = &private_data->xtal_div3.hw;
>> +        xtal_clk_sel_mux_parents[1].fw_name = "xtal";
>> +
>> +        private_data->xtal_clk_sel_mux.reg = port->membase + 
>> AML_UART_REG5;
>> +        private_data->xtal_clk_sel_mux.mask = 0x1;
>> +        private_data->xtal_clk_sel_mux.shift = 26;
>> +        private_data->xtal_clk_sel_mux.flags = CLK_MUX_ROUND_CLOSEST;
>> +        ret = meson_uart_register_clk(port, "xtal_clk_sel",
>> +                          xtal_clk_sel_mux_parents,
>> +                          ARRAY_SIZE(xtal_clk_sel_mux_parents),
>> +                          &clk_mux_ops,
>> +                          &private_data->xtal_clk_sel_mux.hw);
>> +        if (ret)
>> +            return ret;
>> +
>> +        xtal2_clk_sel_mux_parents[0].hw = 
>> &private_data->xtal_clk_sel_mux.hw;
>> +        xtal2_clk_sel_mux_parents[1].hw = &private_data->xtal_div2.hw;
>> +
>> +        private_data->xtal2_clk_sel_mux.reg = port->membase + 
>> AML_UART_REG5;
>> +        private_data->xtal2_clk_sel_mux.mask = 0x1;
>> +        private_data->xtal2_clk_sel_mux.shift = 27;
>> +        private_data->xtal2_clk_sel_mux.flags = CLK_MUX_ROUND_CLOSEST;
>> +        ret = meson_uart_register_clk(port, "xtal2_clk_sel",
>> +                          xtal2_clk_sel_mux_parents,
>> +                          ARRAY_SIZE(xtal2_clk_sel_mux_parents),
>> +                          &clk_mux_ops,
>> +                          &private_data->xtal2_clk_sel_mux.hw);
>> +        if (ret)
>> +            return ret;
>> +
>> +        use_xtal_mux_parents[1].hw = 
>> &private_data->xtal2_clk_sel_mux.hw;
>> +    } else {
>> +        use_xtal_mux_parents[1].hw = &private_data->xtal_div3.hw;
>> +    }
>> +
>> +    private_data->use_xtal_mux.reg = port->membase + AML_UART_REG5;
>> +    private_data->use_xtal_mux.mask = 0x1;
>> +    private_data->use_xtal_mux.shift = 24;
>> +    private_data->use_xtal_mux.flags = CLK_MUX_ROUND_CLOSEST;
>> +    ret = meson_uart_register_clk(port, "use_xtal", 
>> use_xtal_mux_parents,
>> +                      ARRAY_SIZE(use_xtal_mux_parents),
>> +                      &clk_mux_ops,
>> +                      &private_data->use_xtal_mux.hw);
>> +    if (ret)
>> +        return ret;
>> +
>> +    baud_div_parent.hw = &private_data->use_xtal_mux.hw;
>> +
>> +    private_data->baud_div.reg = port->membase + AML_UART_REG5;
>> +    private_data->baud_div.shift = 0;
>> +    private_data->baud_div.width = 23;
>> +    private_data->baud_div.flags = CLK_DIVIDER_ROUND_CLOSEST;
>> +    ret = meson_uart_register_clk(port, "baud_div",
>> +                      &baud_div_parent, 1,
>> +                      &clk_divider_ops,
>> +                      &private_data->baud_div.hw);
>> +    if (ret)
>> +        return ret;
>> +
>> +    private_data->baud_clk = devm_clk_hw_get_clk(port->dev,
>> +                             &private_data->baud_div.hw,
>> +                             "baud_rate");
>> +    if (IS_ERR(private_data->baud_clk))
>> +        return dev_err_probe(port->dev,
>> +                     PTR_ERR(private_data->baud_clk),
>> +                     "Failed to request the 'baud_rate' clock\n");
>>       return 0;
>>   }
>>   static int meson_uart_probe(struct platform_device *pdev)
>>   {
>> +    struct meson_uart_data *private_data;
>>       struct resource *res_mem, *res_irq;
>> +    struct clk *clk_baud, *clk_xtal;
>> +    bool register_clk81_div4;
>>       struct uart_port *port;
>>       int ret = 0;
>>       int id = -1;
>> @@ -711,18 +855,37 @@ static int meson_uart_probe(struct 
>> platform_device *pdev)
>>           return -EBUSY;
>>       }
>> -    port = devm_kzalloc(&pdev->dev, sizeof(struct uart_port), 
>> GFP_KERNEL);
>> -    if (!port)
>> +    private_data = devm_kzalloc(&pdev->dev, sizeof(*private_data),
>> +                    GFP_KERNEL);
>> +    if (!private_data)
>>           return -ENOMEM;
>> +    if (device_get_match_data(&pdev->dev))
>> +        private_data->has_xtal_clk_sel = true;
>> +
>> +    private_data->pclk = devm_clk_get(&pdev->dev, "pclk");
>> +    if (IS_ERR(private_data->pclk))
>> +        return dev_err_probe(&pdev->dev, PTR_ERR(private_data->pclk),
>> +                     "Failed to get the 'pclk' clock\n");
>> +
>> +    clk_baud = devm_clk_get(&pdev->dev, "baud");
>> +    if (IS_ERR(clk_baud))
>> +        return dev_err_probe(&pdev->dev, PTR_ERR(clk_baud),
>> +                     "Failed to get the 'baud' clock\n");
>> +
>> +    clk_xtal = devm_clk_get(&pdev->dev, "xtal");
>> +    if (IS_ERR(clk_xtal))
>> +        return dev_err_probe(&pdev->dev, PTR_ERR(clk_xtal),
>> +                     "Failed to get the 'xtal' clock\n");
>> +
>> +    register_clk81_div4 = clk_get_rate(clk_xtal) != 
>> clk_get_rate(clk_baud);
>> +
>> +    port = &private_data->port;
>> +
>>       port->membase = devm_ioremap_resource(&pdev->dev, res_mem);
>>       if (IS_ERR(port->membase))
>>           return PTR_ERR(port->membase);
>> -    ret = meson_uart_probe_clocks(pdev, port);
>> -    if (ret)
>> -        return ret;
>> -
>>       port->iotype = UPIO_MEM;
>>       port->mapbase = res_mem->start;
>>       port->mapsize = resource_size(res_mem);
>> @@ -735,6 +898,12 @@ static int meson_uart_probe(struct 
>> platform_device *pdev)
>>       port->x_char = 0;
>>       port->ops = &meson_uart_ops;
>>       port->fifosize = 64;
>> +    port->uartclk = clk_get_rate(clk_baud);
>> +    port->private_data = private_data;
>> +
>> +    ret = meson_uart_probe_clocks(port, register_clk81_div4);
>> +    if (ret)
>> +        return ret;
>>       meson_ports[pdev->id] = port;
>>       platform_set_drvdata(pdev, port);
>> @@ -761,10 +930,34 @@ static int meson_uart_remove(struct 
>> platform_device *pdev)
>>   }
>>   static const struct of_device_id meson_uart_dt_match[] = {
>> -    { .compatible = "amlogic,meson6-uart" },
>> -    { .compatible = "amlogic,meson8-uart" },
>> -    { .compatible = "amlogic,meson8b-uart" },
>> -    { .compatible = "amlogic,meson-gx-uart" },
> 
> You can't drop used item without patch for dts files.
> 
> arch/arm64/boot/dts/amlogic$ grep amlogic,meson-gx-uart *|wc -l
> 16
> You're right. I was thoughtless. I'm going to add this delete. Delete 
after changing DTS.
>> +    {
>> +        .compatible = "amlogic,meson6-uart",
>> +        .data = (void *)false,
>> +    },
>> +    {
>> +        .compatible = "amlogic,meson8-uart",
>> +        .data = (void *)false,
>> +    },
>> +    {
>> +        .compatible = "amlogic,meson8b-uart",
>> +        .data = (void *)false,
>> +    },
>> +    {
>> +        .compatible = "amlogic,meson-gxbb-uart",
>> +        .data = (void *)false,
>> +    },
>> +    {
>> +        .compatible = "amlogic,meson-gxl-uart",
>> +        .data = (void *)true,
>> +    },
>> +    {
>> +        .compatible = "amlogic,meson-g12a-uart",
>> +        .data = (void *)true,
>> +    },
>> +    {
>> +        .compatible = "amlogic,meson-s4-uart",
>> +        .data = (void *)true,
>> +    },
>>       { /* sentinel */ },
>>   };
>>   MODULE_DEVICE_TABLE(of, meson_uart_dt_match);
>