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Subject[PATCH v1 1/7] i2c-mlxbf.c: Fix frequency calculation
Date
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.

Reviewed-by: Khalil Blaiech <kblaiech@nvidia.com>
Signed-off-by: Asmaa Mnebhi <asmaa@nvidia.com>
---
drivers/i2c/busses/i2c-mlxbf.c | 59 ++++++++++++----------------------
1 file changed, 21 insertions(+), 38 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mlxbf.c b/drivers/i2c/busses/i2c-mlxbf.c
index 8716032f030a..2e2ac45d9ca0 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
@@ -1407,24 +1400,19 @@ 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:
@@ -1436,31 +1424,26 @@ 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:
@@ -1472,7 +1455,7 @@ 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;
--
2.30.1
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