]> git.ipfire.org Git - thirdparty/kernel/linux.git/commitdiff
clk: lmk04832: add support for digital delay
authorLiam Beguin <lvb@xiphos.com>
Fri, 23 Apr 2021 00:40:56 +0000 (20:40 -0400)
committerStephen Boyd <sboyd@kernel.org>
Mon, 28 Jun 2021 01:02:50 +0000 (18:02 -0700)
The digital delay allows outputs to be delayed from 8 to 1023 VCO
cycles. The delay step can be as small as half the period of the clock
distribution path. For example, a 3.2-GHz VCO frequency results in
156.25-ps steps.  The digital delay value takes effect on the clock
output phase after a SYNC event.

This is required to support JESD204B subclass 1.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
Link: https://lore.kernel.org/r/20210423004057.283926-3-liambeguin@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
drivers/clk/clk-lmk04832.c

index ae80af7f89fb9a9dd5b51288c00f6db737ffdf0a..0cd76e626c3dff716926e2906b3343767fe09b88 100644 (file)
 #define LMK04832_REG_CLKOUT_CTRL0(ch)  (0x100 + (ch >> 1) * 8)
 #define LMK04832_BIT_DCLK_DIV_LSB              GENMASK(7, 0)
 #define LMK04832_REG_CLKOUT_CTRL1(ch)  (0x101 + (ch >> 1) * 8)
+#define LMK04832_BIT_DCLKX_Y_DDLY_LSB          GENMASK(7, 0)
 #define LMK04832_REG_CLKOUT_CTRL2(ch)  (0x102 + (ch >> 1) * 8)
 #define LMK04832_BIT_CLKOUTX_Y_PD              BIT(7)
+#define LMK04832_BIT_DCLKX_Y_DDLY_PD           BIT(4)
+#define LMK04832_BIT_DCLKX_Y_DDLY_MSB          GENMASK(3, 2)
 #define LMK04832_BIT_DCLK_DIV_MSB              GENMASK(1, 0)
 #define LMK04832_REG_CLKOUT_SRC_MUX(ch)        (0x103 + (ch % 2) + (ch >> 1) * 8)
 #define LMK04832_BIT_CLKOUT_SRC_MUX            BIT(5)
 #define LMK04832_REG_CLKOUT_CTRL3(ch)  (0x103 + (ch >> 1) * 8)
 #define LMK04832_BIT_DCLKX_Y_PD                        BIT(4)
 #define LMK04832_BIT_DCLKX_Y_DCC               BIT(2)
+#define LMK04832_BIT_DCLKX_Y_HS                        BIT(0)
 #define LMK04832_REG_CLKOUT_CTRL4(ch)  (0x104 + (ch >> 1) * 8)
 #define LMK04832_BIT_SCLK_PD                   BIT(4)
+#define LMK04832_BIT_SCLKX_Y_DIS_MODE          GENMASK(3, 2)
+#define LMK04832_REG_SCLKX_Y_ADLY(ch)  (0x105 + (ch >> 1) * 8)
+#define LMK04832_REG_SCLKX_Y_DDLY(ch)  (0x106 + (ch >> 1) * 8)
+#define LMK04832_BIT_SCLKX_Y_DDLY              GENMASK(3, 0)
 #define LMK04832_REG_CLKOUT_FMT(ch)    (0x107 + (ch >> 1) * 8)
 #define LMK04832_BIT_CLKOUT_FMT(ch)            (ch % 2 ? 0xf0 : 0x0f)
 #define LMK04832_VAL_CLKOUT_FMT_POWERDOWN              0x00
 #define LMK04832_VAL_VCO_MUX_VCO1                      0x01
 #define LMK04832_VAL_VCO_MUX_EXT                       0x02
 #define LMK04832_REG_SYSREF_OUT                0x139
+#define LMK04832_BIT_SYSREF_REQ_EN             BIT(6)
 #define LMK04832_BIT_SYSREF_MUX                        GENMASK(1, 0)
+#define LMK04832_VAL_SYSREF_MUX_NORMAL_SYNC            0x00
+#define LMK04832_VAL_SYSREF_MUX_RECLK                  0x01
+#define LMK04832_VAL_SYSREF_MUX_PULSER                 0x02
 #define LMK04832_VAL_SYSREF_MUX_CONTINUOUS             0x03
 #define LMK04832_REG_SYSREF_DIV_MSB    0x13a
 #define LMK04832_BIT_SYSREF_DIV_MSB            GENMASK(4, 0)
 #define LMK04832_REG_SYSREF_DIV_LSB    0x13b
+#define LMK04832_REG_SYSREF_DDLY_MSB   0x13c
+#define LMK04832_BIT_SYSREF_DDLY_MSB           GENMASK(4, 0)
+#define LMK04832_REG_SYSREF_DDLY_LSB   0x13d
+#define LMK04832_REG_SYSREF_PULSE_CNT  0x13e
 #define LMK04832_REG_FB_CTRL           0x13f
 #define LMK04832_BIT_PLL2_RCLK_MUX             BIT(7)
 #define LMK04832_VAL_PLL2_RCLK_MUX_OSCIN               0x00
 #define LMK04832_BIT_SYSREF_DDLY_PD            BIT(1)
 #define LMK04832_BIT_SYSREF_PLSR_PD            BIT(0)
 #define LMK04832_REG_SYNC              0x143
+#define LMK04832_BIT_SYNC_CLR                  BIT(7)
+#define LMK04832_BIT_SYNC_1SHOT_EN             BIT(6)
+#define LMK04832_BIT_SYNC_POL                  BIT(5)
 #define LMK04832_BIT_SYNC_EN                   BIT(4)
+#define LMK04832_BIT_SYNC_MODE                 GENMASK(1, 0)
+#define LMK04832_VAL_SYNC_MODE_OFF                     0x00
+#define LMK04832_VAL_SYNC_MODE_ON                      0x01
+#define LMK04832_VAL_SYNC_MODE_PULSER_PIN              0x02
+#define LMK04832_VAL_SYNC_MODE_PULSER_SPI              0x03
 #define LMK04832_REG_SYNC_DIS          0x144
 
 /* 0x146 - 0x14a CLKin Control */
 #define LMK04832_BIT_PLL2_N_0                  GENMASK(1, 0)
 #define LMK04832_REG_PLL2_N_1          0x167
 #define LMK04832_REG_PLL2_N_2          0x168
+#define LMK04832_REG_PLL2_DLD_CNT_MSB  0x16a
 #define LMK04832_REG_PLL2_DLD_CNT_LSB  0x16b
 #define LMK04832_REG_PLL2_LD           0x16e
 #define LMK04832_BIT_PLL2_LD_MUX               GENMASK(7, 3)
@@ -204,6 +229,11 @@ struct lmk_clkout {
  *
  * @dev: reference to a struct device, linked to the spi_device
  * @regmap: struct regmap instance use to access the chip
+ * @sync_mode: operational mode for SYNC signal
+ * @sysref_mux: select SYSREF source
+ * @sysref_pulse_cnt: number of SYSREF pulses generated while not in continuous
+ *                    mode.
+ * @sysref_ddly: SYSREF digital delay value
  * @oscin: PLL2 input clock
  * @vco: reference to the internal VCO clock
  * @sclk: reference to the internal sysref clock (SCLK)
@@ -218,6 +248,11 @@ struct lmk04832 {
        struct device *dev;
        struct regmap *regmap;
 
+       unsigned int sync_mode;
+       unsigned int sysref_mux;
+       unsigned int sysref_pulse_cnt;
+       unsigned int sysref_ddly;
+
        struct clk *oscin;
        struct clk_hw vco;
        struct clk_hw sclk;
@@ -614,6 +649,212 @@ static int lmk04832_register_vco(struct lmk04832 *lmk)
        return devm_clk_hw_register(lmk->dev, &lmk->vco);
 }
 
+static int lmk04832_clkout_set_ddly(struct lmk04832 *lmk, int id)
+{
+       int dclk_div_adj[] = {0, 0, -2, -2, 0, 3, -1, 0};
+       unsigned int sclkx_y_ddly = 10;
+       unsigned int dclkx_y_ddly;
+       unsigned int dclkx_y_div;
+       unsigned int sysref_ddly;
+       unsigned int dclkx_y_hs;
+       unsigned int lsb, msb;
+       int ret;
+
+       ret = regmap_update_bits(lmk->regmap,
+                                LMK04832_REG_CLKOUT_CTRL2(id),
+                                LMK04832_BIT_DCLKX_Y_DDLY_PD,
+                                FIELD_PREP(LMK04832_BIT_DCLKX_Y_DDLY_PD, 0));
+       if (ret)
+               return ret;
+
+       ret = regmap_read(lmk->regmap, LMK04832_REG_SYSREF_DDLY_LSB, &lsb);
+       if (ret)
+               return ret;
+
+       ret = regmap_read(lmk->regmap, LMK04832_REG_SYSREF_DDLY_MSB, &msb);
+       if (ret)
+               return ret;
+
+       sysref_ddly = FIELD_GET(LMK04832_BIT_SYSREF_DDLY_MSB, msb) << 8 | lsb;
+
+       ret = regmap_read(lmk->regmap, LMK04832_REG_CLKOUT_CTRL0(id), &lsb);
+       if (ret)
+               return ret;
+
+       ret = regmap_read(lmk->regmap, LMK04832_REG_CLKOUT_CTRL2(id), &msb);
+       if (ret)
+               return ret;
+
+       dclkx_y_div = FIELD_GET(LMK04832_BIT_DCLK_DIV_MSB, msb) << 8 | lsb;
+
+       ret = regmap_read(lmk->regmap, LMK04832_REG_CLKOUT_CTRL3(id), &lsb);
+       if (ret)
+               return ret;
+
+       dclkx_y_hs = FIELD_GET(LMK04832_BIT_DCLKX_Y_HS, lsb);
+
+       dclkx_y_ddly = sysref_ddly + 1 -
+               dclk_div_adj[dclkx_y_div < 6 ?  dclkx_y_div : 7] -
+               dclkx_y_hs + sclkx_y_ddly;
+
+       if (dclkx_y_ddly < 7 || dclkx_y_ddly > 0x3fff) {
+               dev_err(lmk->dev, "DCLKX_Y_DDLY out of range (%d)\n",
+                       dclkx_y_ddly);
+               return -EINVAL;
+       }
+
+       ret = regmap_write(lmk->regmap,
+                          LMK04832_REG_SCLKX_Y_DDLY(id),
+                          FIELD_GET(LMK04832_BIT_SCLKX_Y_DDLY, sclkx_y_ddly));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(lmk->regmap, LMK04832_REG_CLKOUT_CTRL1(id),
+                               FIELD_GET(0x00ff, dclkx_y_ddly));
+       if (ret)
+               return ret;
+
+       dev_dbg(lmk->dev, "clkout%02u: sysref_ddly=%u, dclkx_y_ddly=%u, "
+               "dclk_div_adj=%+d, dclkx_y_hs=%u, sclkx_y_ddly=%u\n",
+               id, sysref_ddly, dclkx_y_ddly,
+               dclk_div_adj[dclkx_y_div < 6 ? dclkx_y_div : 7],
+               dclkx_y_hs, sclkx_y_ddly);
+
+       return regmap_update_bits(lmk->regmap, LMK04832_REG_CLKOUT_CTRL2(id),
+                                 LMK04832_BIT_DCLKX_Y_DDLY_MSB,
+                                 FIELD_GET(0x0300, dclkx_y_ddly));
+}
+
+/** lmk04832_sclk_sync - Establish deterministic phase relationship between sclk
+ *                       and dclk
+ *
+ * @lmk: Reference to the lmk device
+ *
+ * The synchronization sequence:
+ * - in the datasheet https://www.ti.com/lit/ds/symlink/lmk04832.pdf, p.31
+ *   (8.3.3.1 How to enable SYSREF)
+ * - Ti forum: https://e2e.ti.com/support/clock-and-timing/f/48/t/970972
+ *
+ * Returns 0 or negative errno.
+ */
+static int lmk04832_sclk_sync_sequence(struct lmk04832 *lmk)
+{
+       int ret;
+       int i;
+
+       /* 1. (optional) mute all sysref_outputs during synchronization */
+       /* 2. Enable and write device clock digital delay to applicable clocks */
+       ret = regmap_update_bits(lmk->regmap, LMK04832_REG_MAIN_PD,
+                                LMK04832_BIT_SYSREF_DDLY_PD,
+                                FIELD_PREP(LMK04832_BIT_SYSREF_DDLY_PD, 0));
+       if (ret)
+               return ret;
+
+       for (i = 0; i < lmk->clk_data->num; i += 2) {
+               ret = lmk04832_clkout_set_ddly(lmk, i);
+               if (ret)
+                       return ret;
+       }
+
+       /*
+        * 3. Configure SYNC_MODE to SYNC_PIN and SYSREF_MUX to Normal SYNC,
+        *    and clear SYSREF_REQ_EN (see 6.)
+        */
+       ret = regmap_update_bits(lmk->regmap, LMK04832_REG_SYSREF_OUT,
+                                LMK04832_BIT_SYSREF_REQ_EN |
+                                LMK04832_BIT_SYSREF_MUX,
+                                FIELD_PREP(LMK04832_BIT_SYSREF_REQ_EN, 0) |
+                                FIELD_PREP(LMK04832_BIT_SYSREF_MUX,
+                                           LMK04832_VAL_SYSREF_MUX_NORMAL_SYNC));
+       if (ret)
+               return ret;
+
+       ret = regmap_update_bits(lmk->regmap, LMK04832_REG_SYNC,
+                                LMK04832_BIT_SYNC_MODE,
+                                FIELD_PREP(LMK04832_BIT_SYNC_MODE,
+                                           LMK04832_VAL_SYNC_MODE_ON));
+       if (ret)
+               return ret;
+
+       /* 4. Clear SYNXC_DISx or applicable clocks and clear SYNC_DISSYSREF */
+       ret = regmap_write(lmk->regmap, LMK04832_REG_SYNC_DIS, 0x00);
+       if (ret)
+               return ret;
+
+       /*
+        * 5. If SCLKX_Y_DDLY != 0, Set SYSREF_CLR=1 for at least 15 clock
+        *    distribution path cycles (VCO cycles), then back to 0. In
+        *    PLL2-only use case, this will be complete in less than one SPI
+        *    transaction. If SYSREF local digital delay is not used, this step
+        *    can be skipped.
+        */
+       ret = regmap_update_bits(lmk->regmap, LMK04832_REG_SYNC,
+                                LMK04832_BIT_SYNC_CLR,
+                                FIELD_PREP(LMK04832_BIT_SYNC_CLR, 0x01));
+       if (ret)
+               return ret;
+
+       ret = regmap_update_bits(lmk->regmap, LMK04832_REG_SYNC,
+                                LMK04832_BIT_SYNC_CLR,
+                                FIELD_PREP(LMK04832_BIT_SYNC_CLR, 0x00));
+       if (ret)
+               return ret;
+
+       /*
+        * 6. Toggle SYNC_POL state between inverted and not inverted.
+        *    If you use an external signal on the SYNC pin instead of toggling
+        *    SYNC_POL, make sure that SYSREF_REQ_EN=0 so that the SYSREF_MUX
+        *    does not shift into continuous SYSREF mode.
+        */
+       ret = regmap_update_bits(lmk->regmap, LMK04832_REG_SYNC,
+                          LMK04832_BIT_SYNC_POL,
+                          FIELD_PREP(LMK04832_BIT_SYNC_POL, 0x01));
+       if (ret)
+               return ret;
+
+       ret = regmap_update_bits(lmk->regmap, LMK04832_REG_SYNC,
+                          LMK04832_BIT_SYNC_POL,
+                          FIELD_PREP(LMK04832_BIT_SYNC_POL, 0x00));
+       if (ret)
+               return ret;
+
+       /* 7. Set all SYNC_DISx=1, including SYNC_DISSYSREF */
+       ret = regmap_write(lmk->regmap, LMK04832_REG_SYNC_DIS, 0xff);
+       if (ret)
+               return ret;
+
+       /* 8. Restore state of SYNC_MODE and SYSREF_MUX to desired values */
+       ret = regmap_update_bits(lmk->regmap, LMK04832_REG_SYSREF_OUT,
+                                LMK04832_BIT_SYSREF_MUX,
+                                FIELD_PREP(LMK04832_BIT_SYSREF_MUX,
+                                           lmk->sysref_mux));
+       if (ret)
+               return ret;
+
+       ret = regmap_update_bits(lmk->regmap, LMK04832_REG_SYNC,
+                                LMK04832_BIT_SYNC_MODE,
+                                FIELD_PREP(LMK04832_BIT_SYNC_MODE,
+                                           lmk->sync_mode));
+       if (ret)
+               return ret;
+
+       /*
+        * 9. (optional) if SCLKx_y_DIS_MODE was used to mute SYSREF outputs
+        *    during the SYNC event, restore SCLKx_y_DIS_MODE=0 for active state,
+        *    or set SYSREF_GBL_PD=0 if SCLKx_y_DIS_MODE is set to a conditional
+        *    option.
+        */
+
+       /*
+        * 10. (optional) To reduce power consumption, after the synchronization
+        *     event is complete, DCLKx_y_DDLY_PD=1 and SYSREF_DDLY_PD=1 disable the
+        *     digital delay counters (which are only used immediately after the
+        *     SYNC pulse to delay the output by some number of VCO counts).
+        */
+
+       return ret;
+}
+
 static int lmk04832_sclk_is_enabled(struct clk_hw *hw)
 {
        struct lmk04832 *lmk = container_of(hw, struct lmk04832, sclk);
@@ -701,8 +942,16 @@ static int lmk04832_sclk_set_rate(struct clk_hw *hw, unsigned long rate,
        if (ret)
                return ret;
 
-       return regmap_write(lmk->regmap, LMK04832_REG_SYSREF_DIV_LSB,
+       ret = regmap_write(lmk->regmap, LMK04832_REG_SYSREF_DIV_LSB,
                            FIELD_GET(0x00ff, sysref_div));
+       if (ret)
+               return ret;
+
+       ret = lmk04832_sclk_sync_sequence(lmk);
+       if (ret)
+               dev_err(lmk->dev, "SYNC sequence failed\n");
+
+       return ret;
 }
 
 static const struct clk_ops lmk04832_sclk_ops = {
@@ -731,18 +980,37 @@ static int lmk04832_register_sclk(struct lmk04832 *lmk)
        ret = regmap_update_bits(lmk->regmap, LMK04832_REG_SYSREF_OUT,
                                 LMK04832_BIT_SYSREF_MUX,
                                 FIELD_PREP(LMK04832_BIT_SYSREF_MUX,
-                                           LMK04832_VAL_SYSREF_MUX_CONTINUOUS));
+                                           lmk->sysref_mux));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(lmk->regmap, LMK04832_REG_SYSREF_DDLY_LSB,
+                          FIELD_GET(0x00ff, lmk->sysref_ddly));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(lmk->regmap, LMK04832_REG_SYSREF_DDLY_MSB,
+                          FIELD_GET(0x1f00, lmk->sysref_ddly));
+       if (ret)
+               return ret;
+
+       ret = regmap_write(lmk->regmap, LMK04832_REG_SYSREF_PULSE_CNT,
+                          ilog2(lmk->sysref_pulse_cnt));
        if (ret)
                return ret;
 
        ret = regmap_update_bits(lmk->regmap, LMK04832_REG_MAIN_PD,
+                                LMK04832_BIT_SYSREF_DDLY_PD |
                                 LMK04832_BIT_SYSREF_PLSR_PD,
-                                LMK04832_BIT_SYSREF_PLSR_PD);
+                                FIELD_PREP(LMK04832_BIT_SYSREF_DDLY_PD, 0) |
+                                FIELD_PREP(LMK04832_BIT_SYSREF_PLSR_PD, 0));
        if (ret)
                return ret;
 
-       ret = regmap_update_bits(lmk->regmap, LMK04832_REG_SYNC,
-                                LMK04832_BIT_SYNC_EN, 0xff);
+       ret = regmap_write(lmk->regmap, LMK04832_REG_SYNC,
+                          FIELD_PREP(LMK04832_BIT_SYNC_POL, 0) |
+                          FIELD_PREP(LMK04832_BIT_SYNC_EN, 1) |
+                          FIELD_PREP(LMK04832_BIT_SYNC_MODE, lmk->sync_mode));
        if (ret)
                return ret;
 
@@ -862,15 +1130,41 @@ static int lmk04832_dclk_set_rate(struct clk_hw *hw, unsigned long rate,
                        return ret;
        }
 
+       /*
+        * While using Divide-by-2 or Divide-by-3 for DCLK_X_Y_DIV, SYNC
+        * procedure requires to first program Divide-by-4 and then back to
+        * Divide-by-2 or Divide-by-3 before doing SYNC.
+        */
+       if (dclk_div == 2 || dclk_div == 3) {
+               ret = regmap_update_bits(lmk->regmap,
+                                        LMK04832_REG_CLKOUT_CTRL2(dclk->id),
+                                        LMK04832_BIT_DCLK_DIV_MSB, 0x00);
+               if (ret)
+                       return ret;
+
+               ret = regmap_write(lmk->regmap,
+                                  LMK04832_REG_CLKOUT_CTRL0(dclk->id), 0x04);
+               if (ret)
+                       return ret;
+       }
+
        ret = regmap_write(lmk->regmap, LMK04832_REG_CLKOUT_CTRL0(dclk->id),
                           FIELD_GET(0x0ff, dclk_div));
        if (ret)
                return ret;
 
-       return regmap_update_bits(lmk->regmap,
+       ret = regmap_update_bits(lmk->regmap,
                                  LMK04832_REG_CLKOUT_CTRL2(dclk->id),
                                  LMK04832_BIT_DCLK_DIV_MSB,
                                  FIELD_GET(0x300, dclk_div));
+       if (ret)
+               return ret;
+
+       ret = lmk04832_sclk_sync_sequence(lmk);
+       if (ret)
+               dev_err(lmk->dev, "SYNC sequence failed\n");
+
+       return ret;
 };
 
 static const struct clk_ops lmk04832_dclk_ops = {
@@ -1153,6 +1447,21 @@ static int lmk04832_probe(struct spi_device *spi)
 
        device_property_read_u32(lmk->dev, "ti,vco-hz", &lmk->vco_rate);
 
+       lmk->sysref_ddly = 8;
+       device_property_read_u32(lmk->dev, "ti,sysref-ddly", &lmk->sysref_ddly);
+
+       lmk->sysref_mux = LMK04832_VAL_SYSREF_MUX_CONTINUOUS;
+       device_property_read_u32(lmk->dev, "ti,sysref-mux",
+                                &lmk->sysref_mux);
+
+       lmk->sync_mode = LMK04832_VAL_SYNC_MODE_OFF;
+       device_property_read_u32(lmk->dev, "ti,sync-mode",
+                                &lmk->sync_mode);
+
+       lmk->sysref_pulse_cnt = 4;
+       device_property_read_u32(lmk->dev, "ti,sysref-pulse-count",
+                                &lmk->sysref_pulse_cnt);
+
        for_each_child_of_node(lmk->dev->of_node, child) {
                int reg;