target/linux/bcm27xx/patches-6.1/950-1258-i2c-designware-Support-non-standard-bus-speeds.patch

   1 From 6868dba87e2765042ac376a4a8427b9b981cd410 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.com>
   3 Date: Tue, 16 Jan 2024 16:03:14 +0000
   4 Subject: [PATCH 1258/1295] i2c: designware: Support non-standard bus speeds
   5
   6 Add support for non-standard bus speeds by treating them as detuned
   7 versions of the slowest standard speed not less than the requested
   8 speed.
   9
  10 Signed-off-by: Phil Elwell <phil@raspberrypi.com>
  11 ---
  12  drivers/i2c/busses/i2c-designware-common.c | 27 ++++++++++++++++++++++
  13  drivers/i2c/busses/i2c-designware-core.h   |  1 +
  14  drivers/i2c/busses/i2c-designware-master.c |  2 +-
  15  3 files changed, 29 insertions(+), 1 deletion(-)
  16
  17 --- a/drivers/i2c/busses/i2c-designware-common.c
  18 +++ b/drivers/i2c/busses/i2c-designware-common.c
  19 @@ -318,6 +318,9 @@ void i2c_dw_adjust_bus_speed(struct dw_i
  20  {
  21         u32 acpi_speed = i2c_dw_acpi_round_bus_speed(dev->dev);
  22         struct i2c_timings *t = &dev->timings;
  23 +       u32 wanted_speed;
  24 +       u32 legal_speed = 0;
  25 +       int i;
  26
  27         /*
  28          * Find bus speed from the "clock-frequency" device property, ACPI
  29 @@ -329,6 +332,30 @@ void i2c_dw_adjust_bus_speed(struct dw_i
  30                 t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);
  31         else
  32                 t->bus_freq_hz = I2C_MAX_FAST_MODE_FREQ;
  33 +
  34 +       wanted_speed = t->bus_freq_hz;
  35 +
  36 +       /* For unsupported speeds, scale down the lowest speed which is faster. */
  37 +       for (i = 0; i < ARRAY_SIZE(supported_speeds); i++) {
  38 +               /* supported speeds is in decreasing order */
  39 +               if (wanted_speed == supported_speeds[i]) {
  40 +                       legal_speed = 0;
  41 +                       break;
  42 +               }
  43 +               if (wanted_speed > supported_speeds[i])
  44 +                       break;
  45 +
  46 +               legal_speed = supported_speeds[i];
  47 +       }
  48 +
  49 +       if (legal_speed) {
  50 +               /*
  51 +                * Pretend this was the requested speed, but preserve the preferred
  52 +                * speed so the clock counts can be scaled.
  53 +                */
  54 +               t->bus_freq_hz = legal_speed;
  55 +               dev->wanted_bus_speed = wanted_speed;
  56 +       }
  57  }
  58  EXPORT_SYMBOL_GPL(i2c_dw_adjust_bus_speed);
  59
  60 --- a/drivers/i2c/busses/i2c-designware-core.h
  61 +++ b/drivers/i2c/busses/i2c-designware-core.h
  62 @@ -287,6 +287,7 @@ struct dw_i2c_dev {
  63         u16                     fp_lcnt;
  64         u16                     hs_hcnt;
  65         u16                     hs_lcnt;
  66 +       u32                     wanted_bus_speed;
  67         int                     (*acquire_lock)(void);
  68         void                    (*release_lock)(void);
  69         int                     semaphore_idx;
  70 --- a/drivers/i2c/busses/i2c-designware-master.c
  71 +++ b/drivers/i2c/busses/i2c-designware-master.c
  72 @@ -41,7 +41,7 @@ static void i2c_dw_configure_fifo_master
  73  static u16 clock_calc(struct dw_i2c_dev *dev, bool want_high)
  74  {
  75         struct i2c_timings *t = &dev->timings;
  76 -       u32 wanted_speed = t->bus_freq_hz;
  77 +       u32 wanted_speed = dev->wanted_bus_speed ?: t->bus_freq_hz;
  78         u32 clk_khz = i2c_dw_clk_rate(dev);
  79         u32 extra_ns = want_high ? t->scl_fall_ns : t->scl_rise_ns;
  80         u32 extra_cycles = (u32)div_u64((u64)clk_khz * extra_ns, 1000000);