diff mbox series

[v1,5/7] drivers: i2c: use i2c frequency table

Message ID 20240807100244.16872-6-kfting@nuvoton.com
State Superseded
Headers show
Series [v1,1/7] i2c: npcm: correct the read/write operation procedure | expand

Commit Message

Tyrone Ting Aug. 7, 2024, 10:02 a.m. UTC
From: Tyrone Ting <kfting@nuvoton.com>

Modify i2c frequency from table parameters
for NPCM i2c modules.

Supported frequencies are:

1. 100KHz
2. 400KHz
3. 1MHz

Signed-off-by: Tyrone Ting <kfting@nuvoton.com>
---
 drivers/i2c/busses/i2c-npcm7xx.c | 226 +++++++++++++++++++------------
 1 file changed, 143 insertions(+), 83 deletions(-)

Comments

Dan Carpenter Aug. 13, 2024, 7:58 a.m. UTC | #1
Hi,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/warp5tw-gmail-com/i2c-npcm-correct-the-read-write-operation-procedure/20240807-182210
base:   https://git.kernel.org/pub/scm/linux/kernel/git/andi.shyti/linux.git i2c/i2c-host
patch link:    https://lore.kernel.org/r/20240807100244.16872-6-kfting%40nuvoton.com
patch subject: [PATCH v1 5/7] drivers: i2c: use i2c frequency table
config: arm-randconfig-r073-20240812 (https://download.01.org/0day-ci/archive/20240813/202408130818.FgDP5uNm-lkp@intel.com/config)
compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project f86594788ce93b696675c94f54016d27a6c21d18)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202408130818.FgDP5uNm-lkp@intel.com/

New smatch warnings:
drivers/i2c/busses/i2c-npcm7xx.c:1956 npcm_i2c_init_clk() error: buffer overflow 'smb_timing' 21 <= 21 (assuming for loop doesn't break)
drivers/i2c/busses/i2c-npcm7xx.c:1973 npcm_i2c_init_clk() error: buffer overflow 'smb_timing' 17 <= 21

Old smatch warnings:
drivers/i2c/busses/i2c-npcm7xx.c:752 npcm_i2c_slave_enable() error: buffer overflow 'npcm_i2caddr' 2 <= 9
drivers/i2c/busses/i2c-npcm7xx.c:1960 npcm_i2c_init_clk() error: buffer overflow 'smb_timing' 21 <= 21 (assuming for loop doesn't break)
drivers/i2c/busses/i2c-npcm7xx.c:1974 npcm_i2c_init_clk() error: buffer overflow 'smb_timing' 17 <= 21
drivers/i2c/busses/i2c-npcm7xx.c:1976 npcm_i2c_init_clk() error: buffer overflow 'smb_timing' 17 <= 21
drivers/i2c/busses/i2c-npcm7xx.c:1979 npcm_i2c_init_clk() error: buffer overflow 'smb_timing' 21 <= 21 (assuming for loop doesn't break)

vim +1956 drivers/i2c/busses/i2c-npcm7xx.c

56a1485b102ed1 Tali Perry          2020-05-27  1919  static int npcm_i2c_init_clk(struct npcm_i2c *bus, u32 bus_freq_hz)
56a1485b102ed1 Tali Perry          2020-05-27  1920  {
a946fe9698f261 Tyrone Ting         2024-08-07  1921  	struct  SMB_TIMING_T *smb_timing;
a946fe9698f261 Tyrone Ting         2024-08-07  1922  	u8   scl_table_cnt = 0, table_size = 0;
a946fe9698f261 Tyrone Ting         2024-08-07  1923  
56a1485b102ed1 Tali Perry          2020-05-27  1924  	u8   fast_mode = 0;
56a1485b102ed1 Tali Perry          2020-05-27  1925  	u32  src_clk_khz;
56a1485b102ed1 Tali Perry          2020-05-27  1926  	u32  bus_freq_khz;
56a1485b102ed1 Tali Perry          2020-05-27  1927  
56a1485b102ed1 Tali Perry          2020-05-27  1928  	src_clk_khz = bus->apb_clk / 1000;
56a1485b102ed1 Tali Perry          2020-05-27  1929  	bus_freq_khz = bus_freq_hz / 1000;
56a1485b102ed1 Tali Perry          2020-05-27  1930  	bus->bus_freq = bus_freq_hz;
56a1485b102ed1 Tali Perry          2020-05-27  1931  
a946fe9698f261 Tyrone Ting         2024-08-07  1932  	switch (bus_freq_hz) {
a946fe9698f261 Tyrone Ting         2024-08-07  1933  	case I2C_MAX_STANDARD_MODE_FREQ:
a946fe9698f261 Tyrone Ting         2024-08-07  1934  		smb_timing = SMB_TIMING_100KHZ;
a946fe9698f261 Tyrone Ting         2024-08-07  1935  		table_size = ARRAY_SIZE(SMB_TIMING_100KHZ);
a946fe9698f261 Tyrone Ting         2024-08-07  1936  		break;
a946fe9698f261 Tyrone Ting         2024-08-07  1937  	case I2C_MAX_FAST_MODE_FREQ:
a946fe9698f261 Tyrone Ting         2024-08-07  1938  		smb_timing = SMB_TIMING_400KHZ;
a946fe9698f261 Tyrone Ting         2024-08-07  1939  		table_size = ARRAY_SIZE(SMB_TIMING_400KHZ);
56a1485b102ed1 Tali Perry          2020-05-27  1940  		fast_mode = I2CCTL3_400K_MODE;
a946fe9698f261 Tyrone Ting         2024-08-07  1941  		break;
a946fe9698f261 Tyrone Ting         2024-08-07  1942  	case I2C_MAX_FAST_MODE_PLUS_FREQ:
a946fe9698f261 Tyrone Ting         2024-08-07  1943  		smb_timing = SMB_TIMING_1000KHZ;
a946fe9698f261 Tyrone Ting         2024-08-07  1944  		table_size = ARRAY_SIZE(SMB_TIMING_1000KHZ);
56a1485b102ed1 Tali Perry          2020-05-27  1945  		fast_mode = I2CCTL3_400K_MODE;
a946fe9698f261 Tyrone Ting         2024-08-07  1946  		break;
a946fe9698f261 Tyrone Ting         2024-08-07  1947  	default:
56a1485b102ed1 Tali Perry          2020-05-27  1948  		return -EINVAL;
56a1485b102ed1 Tali Perry          2020-05-27  1949  	}
56a1485b102ed1 Tali Perry          2020-05-27  1950  
a946fe9698f261 Tyrone Ting         2024-08-07  1951  	for (scl_table_cnt = 0 ; scl_table_cnt < table_size ; scl_table_cnt++)
a946fe9698f261 Tyrone Ting         2024-08-07  1952  		if (bus->apb_clk >= smb_timing[scl_table_cnt].core_clk)
a946fe9698f261 Tyrone Ting         2024-08-07  1953  			break;

The minimum smb_timing[scl_table_cnt].core_clk value is 10000000 or 20000000 so
I can't tell just from the context that we are always going to hit this break
statement.

a946fe9698f261 Tyrone Ting         2024-08-07  1954  
56a1485b102ed1 Tali Perry          2020-05-27  1955  	/* write sclfrq value. bits [6:0] are in I2CCTL2 reg */
a946fe9698f261 Tyrone Ting         2024-08-07 @1956  	iowrite8(FIELD_PREP(I2CCTL2_SCLFRQ6_0, smb_timing[scl_table_cnt].sclfrq & 0x7F),
                                                                                               ^^^^^^^^^^^^^^^^^^^^^^^^^

56a1485b102ed1 Tali Perry          2020-05-27  1957  		 bus->reg + NPCM_I2CCTL2);
56a1485b102ed1 Tali Perry          2020-05-27  1958  
56a1485b102ed1 Tali Perry          2020-05-27  1959  	/* bits [8:7] are in I2CCTL3 reg */
a946fe9698f261 Tyrone Ting         2024-08-07  1960  	iowrite8(fast_mode | FIELD_PREP(I2CCTL3_SCLFRQ8_7, (smb_timing[scl_table_cnt].sclfrq >> 7)
a946fe9698f261 Tyrone Ting         2024-08-07  1961  		 & 0x3),
56a1485b102ed1 Tali Perry          2020-05-27  1962  		 bus->reg + NPCM_I2CCTL3);
56a1485b102ed1 Tali Perry          2020-05-27  1963  
56a1485b102ed1 Tali Perry          2020-05-27  1964  	/* Select Bank 0 to access NPCM_I2CCTL4/NPCM_I2CCTL5 */
56a1485b102ed1 Tali Perry          2020-05-27  1965  	npcm_i2c_select_bank(bus, I2C_BANK_0);
56a1485b102ed1 Tali Perry          2020-05-27  1966  
56a1485b102ed1 Tali Perry          2020-05-27  1967  	if (bus_freq_hz >= I2C_MAX_FAST_MODE_FREQ) {
56a1485b102ed1 Tali Perry          2020-05-27  1968  		/*
56a1485b102ed1 Tali Perry          2020-05-27  1969  		 * Set SCL Low/High Time:
56a1485b102ed1 Tali Perry          2020-05-27  1970  		 * k1 = 2 * SCLLT7-0 -> Low Time  = k1 / 2
56a1485b102ed1 Tali Perry          2020-05-27  1971  		 * k2 = 2 * SCLLT7-0 -> High Time = k2 / 2
56a1485b102ed1 Tali Perry          2020-05-27  1972  		 */
a946fe9698f261 Tyrone Ting         2024-08-07 @1973  		iowrite8(smb_timing[scl_table_cnt].scllt, bus->reg + NPCM_I2CSCLLT);
a946fe9698f261 Tyrone Ting         2024-08-07  1974  		iowrite8(smb_timing[scl_table_cnt].sclht, bus->reg + NPCM_I2CSCLHT);
56a1485b102ed1 Tali Perry          2020-05-27  1975  
a946fe9698f261 Tyrone Ting         2024-08-07  1976  		iowrite8(smb_timing[scl_table_cnt].dbcnt, bus->reg + NPCM_I2CCTL5);
56a1485b102ed1 Tali Perry          2020-05-27  1977  	}
56a1485b102ed1 Tali Perry          2020-05-27  1978  
a946fe9698f261 Tyrone Ting         2024-08-07  1979  	iowrite8(smb_timing[scl_table_cnt].hldt, bus->reg + NPCM_I2CCTL4);
56a1485b102ed1 Tali Perry          2020-05-27  1980  
56a1485b102ed1 Tali Perry          2020-05-27  1981  	/* Return to Bank 1, and stay there by default: */
56a1485b102ed1 Tali Perry          2020-05-27  1982  	npcm_i2c_select_bank(bus, I2C_BANK_1);
56a1485b102ed1 Tali Perry          2020-05-27  1983  
56a1485b102ed1 Tali Perry          2020-05-27  1984  	return 0;
56a1485b102ed1 Tali Perry          2020-05-27  1985  }
diff mbox series

Patch

diff --git a/drivers/i2c/busses/i2c-npcm7xx.c b/drivers/i2c/busses/i2c-npcm7xx.c
index c6f72c0e3464..1537fb7baa8c 100644
--- a/drivers/i2c/busses/i2c-npcm7xx.c
+++ b/drivers/i2c/busses/i2c-npcm7xx.c
@@ -261,6 +261,121 @@  static const int npcm_i2caddr[I2C_NUM_OWN_ADDR] = {
 #define I2C_FREQ_MIN_HZ			10000
 #define I2C_FREQ_MAX_HZ			I2C_MAX_FAST_MODE_PLUS_FREQ
 
+struct SMB_TIMING_T {
+	u32 core_clk;
+	u8 hldt;
+	u8 dbcnt;
+	u16 sclfrq;
+	u8 scllt;
+	u8 sclht;
+	bool fast_mode;
+};
+
+static struct SMB_TIMING_T SMB_TIMING_100KHZ[] = {
+	{.core_clk = 100000000, .hldt = 0x2A, .dbcnt = 0x4, .sclfrq = 0xFB, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 62500000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x9D, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 50000000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x7E, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 48000000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x79, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 40000000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x65, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 30000000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x4C, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 29000000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x49, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 26000000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x42, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 25000000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x3F, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 24000000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x3D, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 20000000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x33, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 16180000,  .hldt = 0x2A, .dbcnt = 0x1, .sclfrq = 0x29, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 15000000,  .hldt = 0x23, .dbcnt = 0x1, .sclfrq = 0x26, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 13000000,  .hldt = 0x1D, .dbcnt = 0x1, .sclfrq = 0x21, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 12000000,  .hldt = 0x1B, .dbcnt = 0x1, .sclfrq = 0x1F, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 10000000,  .hldt = 0x18, .dbcnt = 0x1, .sclfrq = 0x1A, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 9000000,   .hldt = 0x16, .dbcnt = 0x1, .sclfrq = 0x17, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 8090000,   .hldt = 0x14, .dbcnt = 0x1, .sclfrq = 0x15, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 7500000,   .hldt = 0x7,  .dbcnt = 0x1, .sclfrq = 0x13, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 6500000,   .hldt = 0xE,  .dbcnt = 0x1, .sclfrq = 0x11, .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false },
+	{.core_clk = 4000000,   .hldt = 0x9,  .dbcnt = 0x1, .sclfrq = 0xB,  .scllt = 0x0,
+	.sclht  = 0x0, .fast_mode = false }
+};
+
+static struct SMB_TIMING_T SMB_TIMING_400KHZ[] = {
+	{.core_clk = 100000000, .hldt = 0x2A, .dbcnt = 0x3, .sclfrq = 0x0, .scllt = 0x47,
+	.sclht  = 0x35, .fast_mode = true },
+	{.core_clk = 62500000,  .hldt = 0x2A, .dbcnt = 0x2, .sclfrq = 0x0, .scllt = 0x2C,
+	.sclht  = 0x22, .fast_mode = true },
+	{.core_clk = 50000000,  .hldt = 0x21, .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x24,
+	.sclht  = 0x1B, .fast_mode = true },
+	{.core_clk = 48000000,  .hldt = 0x1E, .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x24,
+	.sclht  = 0x19, .fast_mode = true },
+	{.core_clk = 40000000,  .hldt = 0x1B, .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x1E,
+	.sclht  = 0x14, .fast_mode = true },
+	{.core_clk = 33000000,  .hldt = 0x15, .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x19,
+	.sclht  = 0x11, .fast_mode = true },
+	{.core_clk = 30000000,  .hldt = 0x15, .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x19,
+	.sclht  = 0xD,  .fast_mode = true },
+	{.core_clk = 29000000,  .hldt = 0x11, .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x15,
+	.sclht  = 0x10, .fast_mode = true },
+	{.core_clk = 26000000,  .hldt = 0x10, .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x13,
+	.sclht  = 0xE,  .fast_mode = true },
+	{.core_clk = 25000000,  .hldt = 0xF,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x13,
+	.sclht  = 0xD,  .fast_mode = true },
+	{.core_clk = 24000000,  .hldt = 0xD,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x12,
+	.sclht  = 0xD,  .fast_mode = true },
+	{.core_clk = 20000000,  .hldt = 0xB,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0xF,
+	.sclht  = 0xA,  .fast_mode = true },
+	{.core_clk = 16180000,  .hldt = 0xA,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0xC,
+	.sclht  = 0x9,  .fast_mode = true },
+	{.core_clk = 15000000,  .hldt = 0x9,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0xB,
+	.sclht  = 0x8,  .fast_mode = true },
+	{.core_clk = 13000000,  .hldt = 0x7,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0xA,
+	.sclht  = 0x7,  .fast_mode = true },
+	{.core_clk = 12000000,  .hldt = 0x7,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0xA,
+	.sclht  = 0x6,  .fast_mode = true },
+	{.core_clk = 10000000,  .hldt = 0x6,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x8,
+	.sclht  = 0x5,  .fast_mode = true },
+};
+
+static struct SMB_TIMING_T SMB_TIMING_1000KHZ[] = {
+	{.core_clk = 100000000, .hldt = 0x15, .dbcnt = 0x4, .sclfrq = 0x0, .scllt = 0x1C,
+	.sclht  = 0x15, .fast_mode = true },
+	{.core_clk = 62500000,  .hldt = 0xF,  .dbcnt = 0x3, .sclfrq = 0x0, .scllt = 0x11,
+	.sclht  = 0xE,  .fast_mode = true },
+	{.core_clk = 50000000,  .hldt = 0xA,  .dbcnt = 0x2, .sclfrq = 0x0, .scllt = 0xE,
+	.sclht  = 0xB,  .fast_mode = true },
+	{.core_clk = 48000000,  .hldt = 0x9,  .dbcnt = 0x2, .sclfrq = 0x0, .scllt = 0xD,
+	.sclht  = 0xB,  .fast_mode = true },
+	{.core_clk = 41000000,  .hldt = 0x9,  .dbcnt = 0x2, .sclfrq = 0x0, .scllt = 0xC,
+	.sclht  = 0x9,  .fast_mode = true },
+	{.core_clk = 40000000,  .hldt = 0x8,  .dbcnt = 0x2, .sclfrq = 0x0, .scllt = 0xB,
+	.sclht  = 0x9,  .fast_mode = true },
+	{.core_clk = 33000000,  .hldt = 0x7,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0xA,
+	.sclht  = 0x7,  .fast_mode = true },
+	{.core_clk = 25000000,  .hldt = 0x4,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x7,
+	.sclht  = 0x6,  .fast_mode = true },
+	{.core_clk = 24000000,  .hldt = 0x7,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x8,
+	.sclht  = 0x5,  .fast_mode = true },
+	{.core_clk = 20000000,  .hldt = 0x4,  .dbcnt = 0x1, .sclfrq = 0x0, .scllt = 0x6,
+	.sclht  = 0x4,  .fast_mode = true },
+};
+
 struct npcm_i2c_data {
 	u8 fifo_size;
 	u32 segctl_init_val;
@@ -1803,11 +1918,9 @@  static void npcm_i2c_recovery_init(struct i2c_adapter *_adap)
  */
 static int npcm_i2c_init_clk(struct npcm_i2c *bus, u32 bus_freq_hz)
 {
-	u32  k1 = 0;
-	u32  k2 = 0;
-	u8   dbnct = 0;
-	u32  sclfrq = 0;
-	u8   hldt = 7;
+	struct  SMB_TIMING_T *smb_timing;
+	u8   scl_table_cnt = 0, table_size = 0;
+
 	u8   fast_mode = 0;
 	u32  src_clk_khz;
 	u32  bus_freq_khz;
@@ -1816,89 +1929,36 @@  static int npcm_i2c_init_clk(struct npcm_i2c *bus, u32 bus_freq_hz)
 	bus_freq_khz = bus_freq_hz / 1000;
 	bus->bus_freq = bus_freq_hz;
 
-	/* 100KHz and below: */
-	if (bus_freq_hz <= I2C_MAX_STANDARD_MODE_FREQ) {
-		sclfrq = src_clk_khz / (bus_freq_khz * 4);
-
-		if (sclfrq < SCLFRQ_MIN || sclfrq > SCLFRQ_MAX)
-			return -EDOM;
-
-		if (src_clk_khz >= 40000)
-			hldt = 17;
-		else if (src_clk_khz >= 12500)
-			hldt = 15;
-		else
-			hldt = 7;
-	}
-
-	/* 400KHz: */
-	else if (bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ) {
-		sclfrq = 0;
+	switch (bus_freq_hz) {
+	case I2C_MAX_STANDARD_MODE_FREQ:
+		smb_timing = SMB_TIMING_100KHZ;
+		table_size = ARRAY_SIZE(SMB_TIMING_100KHZ);
+		break;
+	case I2C_MAX_FAST_MODE_FREQ:
+		smb_timing = SMB_TIMING_400KHZ;
+		table_size = ARRAY_SIZE(SMB_TIMING_400KHZ);
 		fast_mode = I2CCTL3_400K_MODE;
-
-		if (src_clk_khz < 7500)
-			/* 400KHZ cannot be supported for core clock < 7.5MHz */
-			return -EDOM;
-
-		else if (src_clk_khz >= 50000) {
-			k1 = 80;
-			k2 = 48;
-			hldt = 12;
-			dbnct = 7;
-		}
-
-		/* Master or Slave with frequency > 25MHz */
-		else if (src_clk_khz > 25000) {
-			hldt = clk_coef(src_clk_khz, 300) + 7;
-			k1 = clk_coef(src_clk_khz, 1600);
-			k2 = clk_coef(src_clk_khz, 900);
-		}
-	}
-
-	/* 1MHz: */
-	else if (bus_freq_hz <= I2C_MAX_FAST_MODE_PLUS_FREQ) {
-		sclfrq = 0;
+		break;
+	case I2C_MAX_FAST_MODE_PLUS_FREQ:
+		smb_timing = SMB_TIMING_1000KHZ;
+		table_size = ARRAY_SIZE(SMB_TIMING_1000KHZ);
 		fast_mode = I2CCTL3_400K_MODE;
-
-		/* 1MHZ cannot be supported for core clock < 24 MHz */
-		if (src_clk_khz < 24000)
-			return -EDOM;
-
-		k1 = clk_coef(src_clk_khz, 620);
-		k2 = clk_coef(src_clk_khz, 380);
-
-		/* Core clk > 40 MHz */
-		if (src_clk_khz > 40000) {
-			/*
-			 * Set HLDT:
-			 * SDA hold time:  (HLDT-7) * T(CLK) >= 120
-			 * HLDT = 120/T(CLK) + 7 = 120 * FREQ(CLK) + 7
-			 */
-			hldt = clk_coef(src_clk_khz, 120) + 7;
-		} else {
-			hldt = 7;
-			dbnct = 2;
-		}
-	}
-
-	/* Frequency larger than 1 MHz is not supported */
-	else
+		break;
+	default:
 		return -EINVAL;
-
-	if (bus_freq_hz >= I2C_MAX_FAST_MODE_FREQ) {
-		k1 = round_up(k1, 2);
-		k2 = round_up(k2 + 1, 2);
-		if (k1 < SCLFRQ_MIN || k1 > SCLFRQ_MAX ||
-		    k2 < SCLFRQ_MIN || k2 > SCLFRQ_MAX)
-			return -EDOM;
 	}
 
+	for (scl_table_cnt = 0 ; scl_table_cnt < table_size ; scl_table_cnt++)
+		if (bus->apb_clk >= smb_timing[scl_table_cnt].core_clk)
+			break;
+
 	/* write sclfrq value. bits [6:0] are in I2CCTL2 reg */
-	iowrite8(FIELD_PREP(I2CCTL2_SCLFRQ6_0, sclfrq & 0x7F),
+	iowrite8(FIELD_PREP(I2CCTL2_SCLFRQ6_0, smb_timing[scl_table_cnt].sclfrq & 0x7F),
 		 bus->reg + NPCM_I2CCTL2);
 
 	/* bits [8:7] are in I2CCTL3 reg */
-	iowrite8(fast_mode | FIELD_PREP(I2CCTL3_SCLFRQ8_7, (sclfrq >> 7) & 0x3),
+	iowrite8(fast_mode | FIELD_PREP(I2CCTL3_SCLFRQ8_7, (smb_timing[scl_table_cnt].sclfrq >> 7)
+		 & 0x3),
 		 bus->reg + NPCM_I2CCTL3);
 
 	/* Select Bank 0 to access NPCM_I2CCTL4/NPCM_I2CCTL5 */
@@ -1910,13 +1970,13 @@  static int npcm_i2c_init_clk(struct npcm_i2c *bus, u32 bus_freq_hz)
 		 * k1 = 2 * SCLLT7-0 -> Low Time  = k1 / 2
 		 * k2 = 2 * SCLLT7-0 -> High Time = k2 / 2
 		 */
-		iowrite8(k1 / 2, bus->reg + NPCM_I2CSCLLT);
-		iowrite8(k2 / 2, bus->reg + NPCM_I2CSCLHT);
+		iowrite8(smb_timing[scl_table_cnt].scllt, bus->reg + NPCM_I2CSCLLT);
+		iowrite8(smb_timing[scl_table_cnt].sclht, bus->reg + NPCM_I2CSCLHT);
 
-		iowrite8(dbnct, bus->reg + NPCM_I2CCTL5);
+		iowrite8(smb_timing[scl_table_cnt].dbcnt, bus->reg + NPCM_I2CCTL5);
 	}
 
-	iowrite8(hldt, bus->reg + NPCM_I2CCTL4);
+	iowrite8(smb_timing[scl_table_cnt].hldt, bus->reg + NPCM_I2CCTL4);
 
 	/* Return to Bank 1, and stay there by default: */
 	npcm_i2c_select_bank(bus, I2C_BANK_1);