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Common: add patch to support dynamic I2C bus speed configuration #2787

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Common: add patch to support dynamic I2C bus speed configuration #2787

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189 changes: 189 additions & 0 deletions ...c40867f41a8741dba16e50bdf/0035-drivers-i2c-npcm4xx-add-per-speed-SCL-timing-and-run.patch
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Original file line number Diff line number Diff line change
@@ -0,0 +1,189 @@
From 9f0bef6a9923177881493bc58ac76051f0d2e490 Mon Sep 17 00:00:00 2001
From: Jim Liu <JJLIU0@nuvoton.com>
Date: Fri, 24 Jul 2026 10:20:49 +0800
Subject: [PATCH] drivers: i2c: npcm4xx: add per-speed SCL timing and runtime
speed shell command

Allow the fast (400K) and fast-plus (1M) modes to use independent SCL
low/high timing values so a single bus can switch speed at runtime and
still apply the correct special timing for each speed.

Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>
---
drivers/i2c/i2c_npcm4xx.c | 32 +++++++++++---
drivers/i2c/i2c_shell.c | 51 +++++++++++++++++++++++
dts/bindings/i2c/nuvoton,npcm4xx-i2c.yaml | 12 +++++-
3 files changed, 88 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/i2c_npcm4xx.c b/drivers/i2c/i2c_npcm4xx.c
index bf0cbb0b5a2..cbfa11b878a 100755
--- a/drivers/i2c/i2c_npcm4xx.c
+++ b/drivers/i2c/i2c_npcm4xx.c
@@ -75,8 +75,10 @@ struct i2c_npcm4xx_config {
uint32_t default_bitrate;
uint8_t irq; /* i2c controller irq */
uint32_t wait_free_time;
- uint32_t scllt;
- uint32_t sclht;
+ uint32_t scllt; /* fast mode (400K) SCL low time, 0 = auto */
+ uint32_t sclht; /* fast mode (400K) SCL high time, 0 = auto */
+ uint32_t scllt_fp; /* fast-plus mode (1M) SCL low time, 0 = auto */
+ uint32_t sclht_fp; /* fast-plus mode (1M) SCL high time, 0 = auto */
uint8_t multi_master;
};

@@ -314,6 +316,8 @@ static void i2c_npcm4xx_set_baudrate(const struct device *dev, uint32_t bus_freq
inst->SMBnCTL4 = 7;
}
} else {
+ uint32_t use_scllt, use_sclht;
+
if (reg_tmp < 5) {
reg_tmp = 5;
} else if (reg_tmp > 255) {
@@ -324,12 +328,26 @@ static void i2c_npcm4xx_set_baudrate(const struct device *dev, uint32_t bus_freq
inst->SMBnCTL3 |= BIT(NPCM4XX_SMBnCTL3_400K_MODE);
SET_FIELD(inst->SMBnCTL2, NPCM4XX_SMBnCTL2_SCLFRQ60_FIELD, 0);
SET_FIELD(inst->SMBnCTL3, NPCM4XX_SMBnCTL3_SCLFRQ87_FIELD, 0);
- if ( (config->scllt == 0) || (config->sclht == 0) ) {
+
+ /* Pick the SCL timing set for the requested speed:
+ * fast-plus (> 400K, e.g. 1M) uses scllt_fp/sclht_fp,
+ * fast (400K) uses scllt/sclht. A value of 0
+ * means "not specified" and falls back to the computed value.
+ */
+ if (bus_freq > 400000) {
+ use_scllt = config->scllt_fp;
+ use_sclht = config->sclht_fp;
+ } else {
+ use_scllt = config->scllt;
+ use_sclht = config->sclht;
+ }
+
+ if ( (use_scllt == 0) || (use_sclht == 0) ) {
inst->SMBnSCLHT = reg_tmp - 3;
inst->SMBnSCLLT = reg_tmp - 1;
} else {
- inst->SMBnSCLHT = config->sclht;
- inst->SMBnSCLLT = config->scllt;
+ inst->SMBnSCLHT = use_sclht;
+ inst->SMBnSCLLT = use_scllt;
}

/* Set HLDT (48MHz, HLDT = 17, Hold Time = 360ns) */
@@ -1287,6 +1305,10 @@ static const struct i2c_driver_api i2c_npcm4xx_driver_api = {
0), \
.sclht = DT_INST_PROP_OR(inst, sclht, \
0), \
+ .scllt_fp = DT_INST_PROP_OR(inst, scllt_fp, \
+ 0), \
+ .sclht_fp = DT_INST_PROP_OR(inst, sclht_fp, \
+ 0), \
.multi_master = DT_INST_PROP_OR(inst, multi_master, 0), \
}; \
\
diff --git a/drivers/i2c/i2c_shell.c b/drivers/i2c/i2c_shell.c
index 489fd10125f..8cb33d65dac 100644
--- a/drivers/i2c/i2c_shell.c
+++ b/drivers/i2c/i2c_shell.c
@@ -18,6 +18,10 @@ LOG_MODULE_REGISTER(i2c_shell, CONFIG_LOG_DEFAULT_LEVEL);

/* Maximum bytes we can write or read at once */
#define MAX_I2C_BYTES 32
+#define ARGV_DEV 1
+#define ARGV_ADDR 2
+#define ARGV_REG 3
+

/*
* This sends I2C messages without any data (i.e. stop condition after
@@ -276,6 +280,49 @@ static int cmd_i2c_read(const struct shell *shell, size_t argc, char **argv)
return 0;
}

+static int cmd_i2c_speed(const struct shell *shell_ctx, size_t argc, char **argv)
+{
+ char *s_dev_name = argv[ARGV_DEV];
+ const struct device *dev;
+ uint32_t dev_config = 0;
+ uint32_t freq;
+ uint32_t speed;
+ int ret;
+
+ dev = device_get_binding(s_dev_name);
+ if (!dev) {
+ shell_error(shell_ctx, "I2C: Device driver %s not found.",
+ s_dev_name);
+ return -ENODEV;
+ }
+
+ /* Input is the bus frequency in Hz (e.g. 100000, 400000, 1000000) */
+ freq = strtoul(argv[ARGV_DEV + 1], NULL, 10);
+
+ if (freq <= 100000) {
+ speed = I2C_SPEED_STANDARD;
+ } else if (freq <= 400000) {
+ speed = I2C_SPEED_FAST;
+ } else if (freq <= 1000000) {
+ speed = I2C_SPEED_FAST_PLUS;
+ } else {
+ shell_error(shell_ctx,
+ "I2C: Unsupported speed %u Hz (max 1000000 Hz)",
+ freq);
+ return -EINVAL;
+ }
+
+ dev_config = I2C_MODE_MASTER | I2C_SPEED_SET(speed);
+ ret = i2c_configure(dev, dev_config);
+ if (ret < 0) {
+ shell_error(shell_ctx, "I2C: Failed to configure device: %s",
+ s_dev_name);
+ return -EIO;
+ }
+ return 0;
+}
+
+
static void device_name_get(size_t idx, struct shell_static_entry *entry);

SHELL_DYNAMIC_CMD_CREATE(dsub_device_name, device_name_get);
@@ -309,6 +356,10 @@ SHELL_STATIC_SUBCMD_SET_CREATE(sub_i2c_cmds,
SHELL_CMD_ARG(write_byte, &dsub_device_name,
"Write a byte to an I2C device",
cmd_i2c_write_byte, 4, 1),
+ SHELL_CMD_ARG(speed, &dsub_device_name,
+ "Configure I2C bus speed\n"
+ "Usage: speed <device> <freq_hz>",
+ cmd_i2c_speed, 3, 0),
SHELL_SUBCMD_SET_END /* Array terminated. */
);

diff --git a/dts/bindings/i2c/nuvoton,npcm4xx-i2c.yaml b/dts/bindings/i2c/nuvoton,npcm4xx-i2c.yaml
index 680c08cba8f..0a1ff632f4e 100644
--- a/dts/bindings/i2c/nuvoton,npcm4xx-i2c.yaml
+++ b/dts/bindings/i2c/nuvoton,npcm4xx-i2c.yaml
@@ -21,11 +21,19 @@ properties:
scllt:
type: int
required: false
- description: value from 5 to 255
+ description: fast mode (400K) SCL low time, value from 5 to 255
sclht:
type: int
required: false
- description: value from 5 to 255
+ description: fast mode (400K) SCL high time, value from 5 to 255
+ scllt_fp:
+ type: int
+ required: false
+ description: fast-plus mode (1M) SCL low time, value from 5 to 255
+ sclht_fp:
+ type: int
+ required: false
+ description: fast-plus mode (1M) SCL high time, value from 5 to 255
multi-master:
type: int
required: false
--
2.34.1

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