Merge tag 'i2cfixes-for-v2024-01-rc2' of https://source.denx.de/u-boot/custodians/u-boot-i2c

i2c updates for v2024.01-rc2

- nuvoton: support standard/fast/fast plus mode
- bootcount: remove legacy i2c driver and implement
  DM based version

Bugfixes:
- designware_i2c: adjust timing calculation
  SPL probing failed on the StarFive VisionFive 2 board
  Heinrich fixed this, by syncing timing calculation with
  linux implementation.

3 files changed, 90 insertions, 9 deletions

diff --git a/drivers/i2c/designware_i2c.c b/drivers/i2c/designware_i2c.c
index e54de42abc..215ce010cb 100644
--- a/drivers/i2c/designware_i2c.c
+++ b/drivers/i2c/designware_i2c.c
@@ -24,6 +24,17 @@
  */
 #define DW_I2C_COMP_TYPE	0x44570140
 
+/*
+ * This constant is used to calculate when during the clock high phase the data
+ * bit shall be read. The value was copied from the Linux v6.5 function
+ * i2c_dw_scl_hcnt() which provides the following explanation:
+ *
+ * "This is just an experimental rule: the tHD;STA period turned out to be
+ * proportinal to (_HCNT + 3). With this setting, we could meet both tHIGH and
+ * tHD;STA timing specs."
+ */
+#define T_HD_STA_OFFSET 3
+
 static int dw_i2c_enable(struct i2c_regs *i2c_base, bool enable)
 {
 	u32 ena = enable ? IC_ENABLE_0B : 0;
@@ -155,10 +166,10 @@ static int dw_i2c_calc_timing(struct dw_i2c *priv, enum i2c_speed_mode mode,
 
 	/*
 	 * Back-solve for hcnt and lcnt according to the following equations:
-	 * SCL_High_time = [(HCNT + IC_*_SPKLEN + 7) * ic_clk] + SCL_Fall_time
+	 * SCL_High_time = [(HCNT + IC_*_SPKLEN + T_HD_STA_OFFSET) * ic_clk] + SCL_Fall_time
 	 * SCL_Low_time = [(LCNT + 1) * ic_clk] - SCL_Fall_time + SCL_Rise_time
 	 */
-	hcnt = min_thigh_cnt - fall_cnt - 7 - spk_cnt;
+	hcnt = min_thigh_cnt - fall_cnt - T_HD_STA_OFFSET - spk_cnt;
 	lcnt = min_tlow_cnt - rise_cnt + fall_cnt - 1;
 
 	if (hcnt < 0 || lcnt < 0) {
@@ -170,13 +181,13 @@ static int dw_i2c_calc_timing(struct dw_i2c *priv, enum i2c_speed_mode mode,
 	 * Now add things back up to ensure the period is hit. If it is off,
 	 * split the difference and bias to lcnt for remainder
 	 */
-	tot = hcnt + lcnt + 7 + spk_cnt + rise_cnt + 1;
+	tot = hcnt + lcnt + T_HD_STA_OFFSET + spk_cnt + rise_cnt + 1;
 
 	if (tot < period_cnt) {
 		diff = (period_cnt - tot) / 2;
 		hcnt += diff;
 		lcnt += diff;
-		tot = hcnt + lcnt + 7 + spk_cnt + rise_cnt + 1;
+		tot = hcnt + lcnt + T_HD_STA_OFFSET + spk_cnt + rise_cnt + 1;
 		lcnt += period_cnt - tot;
 	}
 
diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c
index 8867a560bd..5405067861 100644
--- a/drivers/i2c/i2c-uclass.c
+++ b/drivers/i2c/i2c-uclass.c
@@ -388,6 +388,81 @@ int i2c_get_chip_for_busnum(int busnum, int chip_addr, uint offset_len,
 	return 0;
 }
 
+/* Find and probe I2C bus based on a chip attached to it */
+static int i2c_get_parent_bus(ofnode chip, struct udevice **devp)
+{
+	ofnode node;
+	struct udevice *dev;
+	int ret;
+
+	node = ofnode_get_parent(chip);
+	if (!ofnode_valid(node))
+		return -ENODEV;
+
+	ret = uclass_get_device_by_ofnode(UCLASS_I2C, node, &dev);
+	if (ret) {
+		*devp = NULL;
+		return ret;
+	}
+
+	*devp = dev;
+	return 0;
+}
+
+int i2c_get_chip_by_phandle(const struct udevice *parent, const char *prop_name,
+			    struct udevice **devp)
+{
+	ofnode node;
+	uint phandle;
+	struct udevice *bus, *chip;
+	char *dev_name;
+	int ret;
+
+	debug("%s: Searching I2C chip for phandle \"%s\"\n",
+	      __func__, prop_name);
+
+	dev_name = strdup(prop_name);
+	if (!dev_name) {
+		ret = -ENOMEM;
+		goto err_exit;
+	}
+
+	ret = dev_read_u32(parent, "i2cbcdev", &phandle);
+	if (ret)
+		goto err_exit;
+
+	node = ofnode_get_by_phandle(phandle);
+	if (!ofnode_valid(node)) {
+		ret = -ENODEV;
+		goto err_exit;
+	}
+
+	ret = i2c_get_parent_bus(node, &bus);
+	if (ret)
+		goto err_exit;
+
+	ret = device_bind_driver_to_node(bus, "i2c_generic_chip_drv",
+					 dev_name, node, &chip);
+	if (ret)
+		goto err_exit;
+
+	ret = device_probe(chip);
+	if (ret) {
+		device_unbind(chip);
+		goto err_exit;
+	}
+
+	debug("%s succeeded\n", __func__);
+	*devp = chip;
+	return 0;
+
+err_exit:
+	free(dev_name);
+	debug("%s failed, ret = %d\n", __func__, ret);
+	*devp = NULL;
+	return ret;
+}
+
 int dm_i2c_probe(struct udevice *bus, uint chip_addr, uint chip_flags,
 		 struct udevice **devp)
 {
diff --git a/drivers/i2c/npcm_i2c.c b/drivers/i2c/npcm_i2c.c
index ea4ef53256..b867b6c8e9 100644
--- a/drivers/i2c/npcm_i2c.c
+++ b/drivers/i2c/npcm_i2c.c
@@ -517,11 +517,6 @@ static int npcm_i2c_init_clk(struct npcm_i2c_bus *bus, u32 bus_freq)
 	u32 sclfrq;
 	u8 hldt, val;
 
-	if (bus_freq > I2C_FREQ_100K) {
-		printf("Support standard mode only\n");
-		return -EINVAL;
-	}
-
 	/* SCLFRQ = T(SCL)/4/T(CLK) = FREQ(CLK)/4/FREQ(SCL) */
 	sclfrq = freq / (bus_freq * 4);
 	if (sclfrq < SCLFRQ_MIN || sclfrq > SCLFRQ_MAX)