Re: [Qemu-devel] [PATCH v5 7/9] hw/misc/zynq_slcr: add clock generation for uarts

[Philippe Mathieu-Daudé]

Hi Damien,

On 10/2/18 4:24 PM, Damien Hedde wrote:
> Add 2 clock outputs for each uart (uart0 & 1):
> + the reference clock
> + the bus interface clock
> 
> The clock frequencies are computed using the internal pll & uart configuration
> registers.
> 
> All clocks depend on the main input clock (ps_clk), which is hard-coded
> to 33.33MHz (zcu102 evaluation board frequency and frequency specified
> in Xilinx's device tree file)

What about adding in zynq_init:

    ClockOut *ps_clk = qdev_init_clock_out(DEVICE(machine), "ps_clk");
    clock_set_frequency(ps_clk, PS_REF_CLK_FREQUENCY);

and later:

    qdev_connect_clock(slcr, "ps_clk",
                       DEVICE(machine), "ps_clk_in", &error_abort);

That would be a more complete example of clock tree.

> 
> Signed-off-by: Damien Hedde <address@hidden>
> ---
>  hw/misc/zynq_slcr.c | 125 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 125 insertions(+)
> 
> diff --git a/hw/misc/zynq_slcr.c b/hw/misc/zynq_slcr.c
> index baa13d1316..0b599ebd97 100644
> --- a/hw/misc/zynq_slcr.c
> +++ b/hw/misc/zynq_slcr.c
> @@ -33,6 +33,8 @@
>          } \
>      } while (0)
>  
> +#define INPUT_PS_REF_CLK_FREQUENCY (33333333)
> +
>  #define XILINX_LOCK_KEY 0x767b
>  #define XILINX_UNLOCK_KEY 0xdf0d
>  
> @@ -44,15 +46,27 @@ REG32(LOCKSTA, 0x00c)
>  REG32(ARM_PLL_CTRL, 0x100)
>  REG32(DDR_PLL_CTRL, 0x104)
>  REG32(IO_PLL_CTRL, 0x108)
> +/* fields for [ARM|DDR|IO_PLL]_CTRL registers */
> +    FIELD(xxx_PLL_CTRL, PLL_RESET, 0, 1)
> +    FIELD(xxx_PLL_CTRL, PLL_PWRDWN, 1, 1)
> +    FIELD(xxx_PLL_CTRL, PLL_BYPASS_QUAL, 3, 1)
> +    FIELD(xxx_PLL_CTRL, PLL_BYPASS_FORCE, 4, 1)
> +    FIELD(xxx_PLL_CTRL, PLL_FPDIV, 12, 7)
>  REG32(PLL_STATUS, 0x10c)
>  REG32(ARM_PLL_CFG, 0x110)
>  REG32(DDR_PLL_CFG, 0x114)
>  REG32(IO_PLL_CFG, 0x118)
>  
>  REG32(ARM_CLK_CTRL, 0x120)
> +    FIELD(ARM_CLK_CTRL, SRCSEL,  4, 2)
> +    FIELD(ARM_CLK_CTRL, DIVISOR, 8, 6)
> +    FIELD(ARM_CLK_CTRL, CPU_1XCLKACT, 27, 1)
> +    FIELD(ARM_CLK_CTRL, CPU_PERI_CLKACT, 28, 1)
>  REG32(DDR_CLK_CTRL, 0x124)
>  REG32(DCI_CLK_CTRL, 0x128)
>  REG32(APER_CLK_CTRL, 0x12c)
> +    FIELD(APER_CLK_CTRL, UART0_CPU1XCLKACT, 20, 1)
> +    FIELD(APER_CLK_CTRL, UART1_CPU1XCLKACT, 21, 1)
>  REG32(USB0_CLK_CTRL, 0x130)
>  REG32(USB1_CLK_CTRL, 0x134)
>  REG32(GEM0_RCLK_CTRL, 0x138)
> @@ -63,12 +77,19 @@ REG32(SMC_CLK_CTRL, 0x148)
>  REG32(LQSPI_CLK_CTRL, 0x14c)
>  REG32(SDIO_CLK_CTRL, 0x150)
>  REG32(UART_CLK_CTRL, 0x154)
> +    FIELD(UART_CLK_CTRL, CLKACT0, 0, 1)
> +    FIELD(UART_CLK_CTRL, CLKACT1, 1, 1)
> +    FIELD(UART_CLK_CTRL, SRCSEL,  4, 2)
> +    FIELD(UART_CLK_CTRL, DIVISOR, 8, 6)
>  REG32(SPI_CLK_CTRL, 0x158)
>  REG32(CAN_CLK_CTRL, 0x15c)
>  REG32(CAN_MIOCLK_CTRL, 0x160)
>  REG32(DBG_CLK_CTRL, 0x164)
>  REG32(PCAP_CLK_CTRL, 0x168)
>  REG32(TOPSW_CLK_CTRL, 0x16c)
> +/* common fields to lots of *_CLK_CTRL registers */
> +    FIELD(xxx_CLK_CTRL, SRCSEL,  4, 2)
> +    FIELD(xxx_CLK_CTRL, DIVISOR, 8, 6)
>  
>  #define FPGA_CTRL_REGS(n, start) \
>      REG32(FPGA ## n ## _CLK_CTRL, (start)) \
> @@ -178,8 +199,92 @@ typedef struct ZynqSLCRState {
>      MemoryRegion iomem;
>  
>      uint32_t regs[ZYNQ_SLCR_NUM_REGS];
> +
> +    ClockOut *uart0_amba_clk;
> +    ClockOut *uart1_amba_clk;
> +    ClockOut *uart0_ref_clk;
> +    ClockOut *uart1_ref_clk;
>  } ZynqSLCRState;
>  
> +/*
> + * return the output frequency of ARM/DDR/IO pll
> + * using input frequency and PLL_CTRL register
> + */
> +static uint64_t zynq_slcr_compute_pll(uint64_t input, uint32_t ctrl_reg)
> +{
> +    uint32_t mult = ((ctrl_reg & R_xxx_PLL_CTRL_PLL_FPDIV_MASK) >>
> +            R_xxx_PLL_CTRL_PLL_FPDIV_SHIFT);
> +
> +    /* first, check if pll is bypassed */
> +    if (ctrl_reg & R_xxx_PLL_CTRL_PLL_BYPASS_FORCE_MASK) {
> +        return input;
> +    }
> +
> +    /* is pll disabled ? */
> +    if (ctrl_reg & (R_xxx_PLL_CTRL_PLL_RESET_MASK |
> +                    R_xxx_PLL_CTRL_PLL_PWRDWN_MASK)) {
> +        return 0;
> +    }
> +
> +    return input * mult;
> +}
> +
> +/*
> + * return the output frequency of a clock given:
> + * + the pll's frequencies in an array corresponding to mux's indexes
> + * + the register xxx_CLK_CTRL value
> + * + enable bit index in ctrl register
> + *
> + * This function make the assumption that ctrl_reg value is organized as 
> follow:
> + * + bits[13:8] clock divisor
> + * + bits[5:4]  clock mux selector (index in array)
> + * + bits[index] clock enable
> + */
> +static uint64_t zynq_slcr_compute_clock(const uint64_t plls[],
> +                                        uint32_t ctrl_reg,
> +                                        unsigned index)
> +{
> +    uint32_t divisor = FIELD_EX32(ctrl_reg, xxx_CLK_CTRL, DIVISOR);
> +    uint32_t srcsel = FIELD_EX32(ctrl_reg, xxx_CLK_CTRL, SRCSEL);
> +
> +    if ((ctrl_reg & (1u << index)) == 0) {
> +        return 0;
> +    }
> +
> +    return plls[srcsel] / (divisor ? divisor : 1u);
> +}
> +
> +#define ZYNQ_CLOCK(_state, _plls, _reg, _enable_field) \
> +    zynq_slcr_compute_clock((_plls), (_state)->regs[R_ ## _reg], \
> +            R_ ## _reg ## _ ## _enable_field ## _SHIFT)
> +#define ZYNQ_GATE(_state, _clk, _reg, _field) \
> +    (ARRAY_FIELD_EX32((_state)->regs, _reg, _field) ? (_clk) : 0)
> +
> +static void zynq_slcr_compute_clocks(ZynqSLCRState *s)
> +{
> +    uint64_t ps_clk = INPUT_PS_REF_CLK_FREQUENCY;
> +    uint64_t io_pll = zynq_slcr_compute_pll(ps_clk, s->regs[R_IO_PLL_CTRL]);
> +    uint64_t arm_pll = zynq_slcr_compute_pll(ps_clk, 
> s->regs[R_ARM_PLL_CTRL]);
> +    uint64_t ddr_pll = zynq_slcr_compute_pll(ps_clk, 
> s->regs[R_DDR_PLL_CTRL]);
> +    uint64_t cpu_mux[4] = {arm_pll, arm_pll, ddr_pll, io_pll};
> +    uint64_t uart_mux[4] = {io_pll, io_pll, arm_pll, ddr_pll};
> +    uint64_t cpu1x_clk;
> +
> +    /* compute uartX amba clocks */
> +    cpu1x_clk = ZYNQ_CLOCK(s, cpu_mux, ARM_CLK_CTRL, CPU_PERI_CLKACT);
> +    cpu1x_clk = ZYNQ_GATE(s, cpu1x_clk, ARM_CLK_CTRL, CPU_1XCLKACT);
> +    clock_set_frequency(s->uart0_amba_clk,
> +            ZYNQ_GATE(s, cpu1x_clk, APER_CLK_CTRL, UART0_CPU1XCLKACT));
> +    clock_set_frequency(s->uart1_amba_clk,
> +            ZYNQ_GATE(s, cpu1x_clk, APER_CLK_CTRL, UART1_CPU1XCLKACT));
> +
> +    /* compute uartX ref clocks */
> +    clock_set_frequency(s->uart0_ref_clk,
> +            ZYNQ_CLOCK(s, uart_mux, UART_CLK_CTRL, CLKACT0));
> +    clock_set_frequency(s->uart1_ref_clk,
> +            ZYNQ_CLOCK(s, uart_mux, UART_CLK_CTRL, CLKACT1));
> +}
> +
>  static void zynq_slcr_reset(DeviceState *d)
>  {
>      ZynqSLCRState *s = ZYNQ_SLCR(d);
> @@ -274,6 +379,8 @@ static void zynq_slcr_reset(DeviceState *d)
>      s->regs[R_DDRIOB + 4] = s->regs[R_DDRIOB + 5] = s->regs[R_DDRIOB + 6]
>                            = 0x00000e00;
>      s->regs[R_DDRIOB + 12] = 0x00000021;
> +
> +    zynq_slcr_compute_clocks(s);
>  }
>  
>  
> @@ -408,6 +515,14 @@ static void zynq_slcr_write(void *opaque, hwaddr offset,
>              qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
>          }
>          break;
> +    case R_IO_PLL_CTRL:
> +    case R_ARM_PLL_CTRL:
> +    case R_DDR_PLL_CTRL:
> +    case R_ARM_CLK_CTRL:
> +    case R_APER_CLK_CTRL:
> +    case R_UART_CLK_CTRL:
> +        zynq_slcr_compute_clocks(s);
> +        break;
>      }
>  }
>  
> @@ -417,6 +532,14 @@ static const MemoryRegionOps slcr_ops = {
>      .endianness = DEVICE_NATIVE_ENDIAN,
>  };
>  
> +static const ClockPortInitArray zynq_slcr_clocks = {
> +    QDEV_CLOCK_OUT(ZynqSLCRState, uart0_amba_clk),
> +    QDEV_CLOCK_OUT(ZynqSLCRState, uart1_amba_clk),
> +    QDEV_CLOCK_OUT(ZynqSLCRState, uart0_ref_clk),
> +    QDEV_CLOCK_OUT(ZynqSLCRState, uart1_ref_clk),
> +    QDEV_CLOCK_END,
> +};
> +
>  static void zynq_slcr_init(Object *obj)
>  {
>      ZynqSLCRState *s = ZYNQ_SLCR(obj);
> @@ -424,6 +547,8 @@ static void zynq_slcr_init(Object *obj)
>      memory_region_init_io(&s->iomem, obj, &slcr_ops, s, "slcr",
>                            ZYNQ_SLCR_MMIO_SIZE);
>      sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->iomem);
> +
> +    qdev_init_clocks(DEVICE(obj), zynq_slcr_clocks);
>  }
>  
>  static const VMStateDescription vmstate_zynq_slcr = {
>