[PATCH 5.15 139/148] i2c: mlxbf: Fix frequency calculation

Greg Kroah-Hartman
2022-09-26T11:30:12Z

From: Asmaa Mnebhi <asmaa@nvidia.com>

[ Upstream commit 37f071ec327b04c83d47637c5e5c2199b39899ca ]

The i2c-mlxbf.c driver is currently broken because there is a bug
in the calculation of the frequency. core_f, core_r and core_od
are components read from hardware registers and are used to
compute the frequency used to compute different timing parameters.
The shifting mechanism used to get core_f, core_r and core_od is
wrong. Use FIELD_GET to mask and shift the bitfields properly.

Fixes: b5b5b32081cd206b (i2c: mlxbf: I2C SMBus driver for Mellanox BlueField SoC)
Reviewed-by: Khalil Blaiech <kblaiech@nvidia.com>
Signed-off-by: Asmaa Mnebhi <asmaa@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/i2c/busses/i2c-mlxbf.c | 63 +++++++++++++---------------------
1 file changed, 23 insertions(+), 40 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mlxbf.c b/drivers/i2c/busses/i2c-mlxbf.c
index ac93c0ccf53c..ad5efd7497d1 100644
--- a/drivers/i2c/busses/i2c-mlxbf.c
+++ b/drivers/i2c/busses/i2c-mlxbf.c
@@ -6,6 +6,7 @@
*/

#include <linux/acpi.h>
+#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
@@ -63,13 +64,14 @@
*/
#define MLXBF_I2C_TYU_PLL_OUT_FREQ (400 * 1000 * 1000)
/* Reference clock for Bluefield - 156 MHz. */
-#define MLXBF_I2C_PLL_IN_FREQ (156 * 1000 * 1000)
+#define MLXBF_I2C_PLL_IN_FREQ 156250000ULL

/* Constant used to determine the PLL frequency. */
-#define MLNXBF_I2C_COREPLL_CONST 16384
+#define MLNXBF_I2C_COREPLL_CONST 16384ULL
+
+#define MLXBF_I2C_FREQUENCY_1GHZ 1000000000ULL

/* PLL registers. */
-#define MLXBF_I2C_CORE_PLL_REG0 0x0
#define MLXBF_I2C_CORE_PLL_REG1 0x4
#define MLXBF_I2C_CORE_PLL_REG2 0x8

@@ -181,22 +183,15 @@
#define MLXBF_I2C_COREPLL_FREQ MLXBF_I2C_TYU_PLL_OUT_FREQ

/* Core PLL TYU configuration. */
-#define MLXBF_I2C_COREPLL_CORE_F_TYU_MASK GENMASK(12, 0)
-#define MLXBF_I2C_COREPLL_CORE_OD_TYU_MASK GENMASK(3, 0)
-#define MLXBF_I2C_COREPLL_CORE_R_TYU_MASK GENMASK(5, 0)
-
-#define MLXBF_I2C_COREPLL_CORE_F_TYU_SHIFT 3
-#define MLXBF_I2C_COREPLL_CORE_OD_TYU_SHIFT 16
-#define MLXBF_I2C_COREPLL_CORE_R_TYU_SHIFT 20
+#define MLXBF_I2C_COREPLL_CORE_F_TYU_MASK GENMASK(15, 3)
+#define MLXBF_I2C_COREPLL_CORE_OD_TYU_MASK GENMASK(19, 16)
+#define MLXBF_I2C_COREPLL_CORE_R_TYU_MASK GENMASK(25, 20)

/* Core PLL YU configuration. */
#define MLXBF_I2C_COREPLL_CORE_F_YU_MASK GENMASK(25, 0)
#define MLXBF_I2C_COREPLL_CORE_OD_YU_MASK GENMASK(3, 0)
-#define MLXBF_I2C_COREPLL_CORE_R_YU_MASK GENMASK(5, 0)
+#define MLXBF_I2C_COREPLL_CORE_R_YU_MASK GENMASK(31, 26)

-#define MLXBF_I2C_COREPLL_CORE_F_YU_SHIFT 0
-#define MLXBF_I2C_COREPLL_CORE_OD_YU_SHIFT 1
-#define MLXBF_I2C_COREPLL_CORE_R_YU_SHIFT 26

/* Core PLL frequency. */
static u64 mlxbf_i2c_corepll_frequency;
@@ -479,8 +474,6 @@ static struct mutex mlxbf_i2c_bus_lock;
#define MLXBF_I2C_MASK_8 GENMASK(7, 0)
#define MLXBF_I2C_MASK_16 GENMASK(15, 0)

-#define MLXBF_I2C_FREQUENCY_1GHZ 1000000000
-
/*
* Function to poll a set of bits at a specific address; it checks whether
* the bits are equal to zero when eq_zero is set to 'true', and not equal
@@ -1410,24 +1403,19 @@ static int mlxbf_i2c_init_master(struct platform_device *pdev,
return 0;
}

-static u64 mlxbf_calculate_freq_from_tyu(struct mlxbf_i2c_resource *corepll_res)
+static u64 mlxbf_i2c_calculate_freq_from_tyu(struct mlxbf_i2c_resource *corepll_res)
{
- u64 core_frequency, pad_frequency;
+ u64 core_frequency;
u8 core_od, core_r;
u32 corepll_val;
u16 core_f;

- pad_frequency = MLXBF_I2C_PLL_IN_FREQ;
-
corepll_val = readl(corepll_res->io + MLXBF_I2C_CORE_PLL_REG1);

/* Get Core PLL configuration bits. */
- core_f = rol32(corepll_val, MLXBF_I2C_COREPLL_CORE_F_TYU_SHIFT) &
- MLXBF_I2C_COREPLL_CORE_F_TYU_MASK;
- core_od = rol32(corepll_val, MLXBF_I2C_COREPLL_CORE_OD_TYU_SHIFT) &
- MLXBF_I2C_COREPLL_CORE_OD_TYU_MASK;
- core_r = rol32(corepll_val, MLXBF_I2C_COREPLL_CORE_R_TYU_SHIFT) &
- MLXBF_I2C_COREPLL_CORE_R_TYU_MASK;
+ core_f = FIELD_GET(MLXBF_I2C_COREPLL_CORE_F_TYU_MASK, corepll_val);
+ core_od = FIELD_GET(MLXBF_I2C_COREPLL_CORE_OD_TYU_MASK, corepll_val);
+ core_r = FIELD_GET(MLXBF_I2C_COREPLL_CORE_R_TYU_MASK, corepll_val);

/*
* Compute PLL output frequency as follow:
@@ -1439,31 +1427,26 @@ static u64 mlxbf_calculate_freq_from_tyu(struct mlxbf_i2c_resource *corepll_res)
* Where PLL_OUT_FREQ and PLL_IN_FREQ refer to CoreFrequency
* and PadFrequency, respectively.
*/
- core_frequency = pad_frequency * (++core_f);
+ core_frequency = MLXBF_I2C_PLL_IN_FREQ * (++core_f);
core_frequency /= (++core_r) * (++core_od);

return core_frequency;
}

-static u64 mlxbf_calculate_freq_from_yu(struct mlxbf_i2c_resource *corepll_res)
+static u64 mlxbf_i2c_calculate_freq_from_yu(struct mlxbf_i2c_resource *corepll_res)
{
u32 corepll_reg1_val, corepll_reg2_val;
- u64 corepll_frequency, pad_frequency;
+ u64 corepll_frequency;
u8 core_od, core_r;
u32 core_f;

- pad_frequency = MLXBF_I2C_PLL_IN_FREQ;
-
corepll_reg1_val = readl(corepll_res->io + MLXBF_I2C_CORE_PLL_REG1);
corepll_reg2_val = readl(corepll_res->io + MLXBF_I2C_CORE_PLL_REG2);

/* Get Core PLL configuration bits */
- core_f = rol32(corepll_reg1_val, MLXBF_I2C_COREPLL_CORE_F_YU_SHIFT) &
- MLXBF_I2C_COREPLL_CORE_F_YU_MASK;
- core_r = rol32(corepll_reg1_val, MLXBF_I2C_COREPLL_CORE_R_YU_SHIFT) &
- MLXBF_I2C_COREPLL_CORE_R_YU_MASK;
- core_od = rol32(corepll_reg2_val, MLXBF_I2C_COREPLL_CORE_OD_YU_SHIFT) &
- MLXBF_I2C_COREPLL_CORE_OD_YU_MASK;
+ core_f = FIELD_GET(MLXBF_I2C_COREPLL_CORE_F_YU_MASK, corepll_reg1_val);
+ core_r = FIELD_GET(MLXBF_I2C_COREPLL_CORE_R_YU_MASK, corepll_reg1_val);
+ core_od = FIELD_GET(MLXBF_I2C_COREPLL_CORE_OD_YU_MASK, corepll_reg2_val);

/*
* Compute PLL output frequency as follow:
@@ -1475,7 +1458,7 @@ static u64 mlxbf_calculate_freq_from_yu(struct mlxbf_i2c_resource *corepll_res)
* Where PLL_OUT_FREQ and PLL_IN_FREQ refer to CoreFrequency
* and PadFrequency, respectively.
*/
- corepll_frequency = (pad_frequency * core_f) / MLNXBF_I2C_COREPLL_CONST;
+ corepll_frequency = (MLXBF_I2C_PLL_IN_FREQ * core_f) / MLNXBF_I2C_COREPLL_CONST;
corepll_frequency /= (++core_r) * (++core_od);

return corepll_frequency;
@@ -2183,14 +2166,14 @@ static struct mlxbf_i2c_chip_info mlxbf_i2c_chip[] = {
[1] = &mlxbf_i2c_corepll_res[MLXBF_I2C_CHIP_TYPE_1],
[2] = &mlxbf_i2c_gpio_res[MLXBF_I2C_CHIP_TYPE_1]
},
- .calculate_freq = mlxbf_calculate_freq_from_tyu
+ .calculate_freq = mlxbf_i2c_calculate_freq_from_tyu
},
[MLXBF_I2C_CHIP_TYPE_2] = {
.type = MLXBF_I2C_CHIP_TYPE_2,
.shared_res = {
[0] = &mlxbf_i2c_corepll_res[MLXBF_I2C_CHIP_TYPE_2]
},
- .calculate_freq = mlxbf_calculate_freq_from_yu
+ .calculate_freq = mlxbf_i2c_calculate_freq_from_yu
}
};

--
2.35.1