hw/misc/zynq_slcr: add clock generation for uarts

Add some clocks to zynq_slcr
+ the main input clock (ps_clk)
+ the reference clock outputs for each uart (uart0 & 1)

This commit also transitional the slcr to multi-phase reset as it is
required to initialize the clocks correctly.

The clock frequencies are computed using the internal pll & uart configuration
registers and the input ps_clk frequency.

Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20200406135251.157596-7-damien.hedde@greensocs.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/misc/zynq_slcr.c

@@ -22,6 +22,7 @@
 #include "qemu/log.h"
 #include "qemu/module.h"
 #include "hw/registerfields.h"
+#include "hw/qdev-clock.h"
 
 #ifndef ZYNQ_SLCR_ERR_DEBUG
 #define ZYNQ_SLCR_ERR_DEBUG 0
@@ -45,6 +46,12 @@ 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)
@@ -64,6 +71,10 @@ 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)
@@ -179,11 +190,127 @@ typedef struct ZynqSLCRState {
     MemoryRegion iomem;
 
     uint32_t regs[ZYNQ_SLCR_NUM_REGS];
+
+    Clock *ps_clk;
+    Clock *uart0_ref_clk;
+    Clock *uart1_ref_clk;
 } ZynqSLCRState;
 
-static void zynq_slcr_reset(DeviceState *d)
+/*
+ * 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)
 {
-    ZynqSLCRState *s = ZYNQ_SLCR(d);
+    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;
+    }
+
+    /* frequency multiplier -> period division */
+    return input / mult;
+}
+
+/*
+ * return the output period of a clock given:
+ * + the periods in an array corresponding to input mux selector
+ * + the register xxx_CLK_CTRL value
+ * + enable bit index in ctrl register
+ *
+ * This function makes the assumption that the ctrl_reg value is organized as
+ * follows:
+ * + bits[13:8]  clock frequency divisor
+ * + bits[5:4]   clock mux selector (index in array)
+ * + bits[index] clock enable
+ */
+static uint64_t zynq_slcr_compute_clock(const uint64_t periods[],
+                                        uint32_t ctrl_reg,
+                                        unsigned index)
+{
+    uint32_t srcsel = extract32(ctrl_reg, 4, 2); /* bits [5:4] */
+    uint32_t divisor = extract32(ctrl_reg, 8, 6); /* bits [13:8] */
+
+    /* first, check if clock is disabled */
+    if (((ctrl_reg >> index) & 1u) == 0) {
+        return 0;
+    }
+
+    /*
+     * according to the Zynq technical ref. manual UG585 v1.12.2 in
+     * Clocks chapter, section 25.10.1 page 705:
+     * "The 6-bit divider provides a divide range of 1 to 63"
+     * We follow here what is implemented in linux kernel and consider
+     * the 0 value as a bypass (no division).
+     */
+    /* frequency divisor -> period multiplication */
+    return periods[srcsel] * (divisor ? divisor : 1u);
+}
+
+/*
+ * macro helper around zynq_slcr_compute_clock to avoid repeating
+ * the register name.
+ */
+#define ZYNQ_COMPUTE_CLK(state, plls, reg, enable_field) \
+    zynq_slcr_compute_clock((plls), (state)->regs[reg], \
+                            reg ## _ ## enable_field ## _SHIFT)
+
+/**
+ * Compute and set the ouputs clocks periods.
+ * But do not propagate them further. Connected clocks
+ * will not receive any updates (See zynq_slcr_compute_clocks())
+ */
+static void zynq_slcr_compute_clocks(ZynqSLCRState *s)
+{
+    uint64_t ps_clk = clock_get(s->ps_clk);
+
+    /* consider outputs clocks are disabled while in reset */
+    if (device_is_in_reset(DEVICE(s))) {
+        ps_clk = 0;
+    }
+
+    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 uart_mux[4] = {io_pll, io_pll, arm_pll, ddr_pll};
+
+    /* compute uartX reference clocks */
+    clock_set(s->uart0_ref_clk,
+              ZYNQ_COMPUTE_CLK(s, uart_mux, R_UART_CLK_CTRL, CLKACT0));
+    clock_set(s->uart1_ref_clk,
+              ZYNQ_COMPUTE_CLK(s, uart_mux, R_UART_CLK_CTRL, CLKACT1));
+}
+
+/**
+ * Propagate the outputs clocks.
+ * zynq_slcr_compute_clocks() should have been called before
+ * to configure them.
+ */
+static void zynq_slcr_propagate_clocks(ZynqSLCRState *s)
+{
+    clock_propagate(s->uart0_ref_clk);
+    clock_propagate(s->uart1_ref_clk);
+}
+
+static void zynq_slcr_ps_clk_callback(void *opaque)
+{
+    ZynqSLCRState *s = (ZynqSLCRState *) opaque;
+    zynq_slcr_compute_clocks(s);
+    zynq_slcr_propagate_clocks(s);
+}
+
+static void zynq_slcr_reset_init(Object *obj, ResetType type)
+{
+    ZynqSLCRState *s = ZYNQ_SLCR(obj);
     int i;
 
     DB_PRINT("RESET\n");
@@ -277,6 +404,23 @@ static void zynq_slcr_reset(DeviceState *d)
     s->regs[R_DDRIOB + 12] = 0x00000021;
 }
 
+static void zynq_slcr_reset_hold(Object *obj)
+{
+    ZynqSLCRState *s = ZYNQ_SLCR(obj);
+
+    /* will disable all output clocks */
+    zynq_slcr_compute_clocks(s);
+    zynq_slcr_propagate_clocks(s);
+}
+
+static void zynq_slcr_reset_exit(Object *obj)
+{
+    ZynqSLCRState *s = ZYNQ_SLCR(obj);
+
+    /* will compute output clocks according to ps_clk and registers */
+    zynq_slcr_compute_clocks(s);
+    zynq_slcr_propagate_clocks(s);
+}
 
 static bool zynq_slcr_check_offset(hwaddr offset, bool rnw)
 {
@@ -409,6 +553,13 @@ 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_UART_CLK_CTRL:
+        zynq_slcr_compute_clocks(s);
+        zynq_slcr_propagate_clocks(s);
+        break;
     }
 }
 
@@ -418,6 +569,13 @@ static const MemoryRegionOps slcr_ops = {
     .endianness = DEVICE_NATIVE_ENDIAN,
 };
 
+static const ClockPortInitArray zynq_slcr_clocks = {
+    QDEV_CLOCK_IN(ZynqSLCRState, ps_clk, zynq_slcr_ps_clk_callback),
+    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);
@@ -425,14 +583,17 @@ 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 = {
     .name = "zynq_slcr",
-    .version_id = 2,
+    .version_id = 3,
     .minimum_version_id = 2,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32_ARRAY(regs, ZynqSLCRState, ZYNQ_SLCR_NUM_REGS),
+        VMSTATE_CLOCK_V(ps_clk, ZynqSLCRState, 3),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -440,9 +601,12 @@ static const VMStateDescription vmstate_zynq_slcr = {
 static void zynq_slcr_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
+    ResettableClass *rc = RESETTABLE_CLASS(klass);
 
     dc->vmsd = &vmstate_zynq_slcr;
-    dc->reset = zynq_slcr_reset;
+    rc->phases.enter = zynq_slcr_reset_init;
+    rc->phases.hold  = zynq_slcr_reset_hold;
+    rc->phases.exit  = zynq_slcr_reset_exit;
 }
 
 static const TypeInfo zynq_slcr_info = {