[PATCH 1/3] i2c: thunderx: Clock divisor logic changes

Piyush Malgujar
2023-03-30T13:43:42Z

From: Suneel Garapati <sgarapati@marvell.com>

Handle changes to clock divisor logic for OcteonTX2 SoC family using
subsystem ID and using default reference clock source as 100MHz.

Signed-off-by: Suneel Garapati <sgarapati@marvell.com>
Signed-off-by: Piyush Malgujar <pmalgujar@marvell.com>
---
drivers/i2c/busses/i2c-octeon-core.c | 29 ++++++++++++++++++++----
drivers/i2c/busses/i2c-octeon-core.h | 15 ++++++++++++
drivers/i2c/busses/i2c-thunderx-pcidrv.c | 6 +++++
3 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-octeon-core.c b/drivers/i2c/busses/i2c-octeon-core.c
index 845eda70b8cab52a0453c9f4cb545010fba4305d..dfd58bbec47b1f0554ae0c100c680b6ba9be61ec 100644
--- a/drivers/i2c/busses/i2c-octeon-core.c
+++ b/drivers/i2c/busses/i2c-octeon-core.c
@@ -17,6 +17,7 @@
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
+#include <linux/pci.h>

#include "i2c-octeon-core.h"

@@ -658,31 +659,51 @@ int octeon_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
void octeon_i2c_set_clock(struct octeon_i2c *i2c)
{
int tclk, thp_base, inc, thp_idx, mdiv_idx, ndiv_idx, foscl, diff;
- int thp = 0x18, mdiv = 2, ndiv = 0, delta_hz = 1000000;
+ int mdiv_min = 2;
+ /* starting value on search for lowest diff */
+ const int huge_delta = 1000000;
+ /*
+ * Find divisors to produce target frequency, start with large delta
+ * to cover wider range of divisors, note thp = TCLK half period.
+ */
+ int thp = 0x18, mdiv = 2, ndiv = 0, delta_hz = huge_delta;
+
+ if (octeon_i2c_is_otx2(to_pci_dev(i2c->dev))) {
+ thp = 0x3;
+ mdiv_min = 0;
+ }

for (ndiv_idx = 0; ndiv_idx < 8 && delta_hz != 0; ndiv_idx++) {
/*
* An mdiv value of less than 2 seems to not work well
* with ds1337 RTCs, so we constrain it to larger values.
*/
- for (mdiv_idx = 15; mdiv_idx >= 2 && delta_hz != 0; mdiv_idx--) {
+ for (mdiv_idx = 15; mdiv_idx >= mdiv_min && delta_hz != 0; mdiv_idx--) {
/*
* For given ndiv and mdiv values check the
* two closest thp values.
*/
tclk = i2c->twsi_freq * (mdiv_idx + 1) * 10;
tclk *= (1 << ndiv_idx);
- thp_base = (i2c->sys_freq / (tclk * 2)) - 1;
+ if (octeon_i2c_is_otx2(to_pci_dev(i2c->dev)))
+ thp_base = (i2c->sys_freq / tclk) - 2;
+ else
+ thp_base = (i2c->sys_freq / (tclk * 2)) - 1;

for (inc = 0; inc <= 1; inc++) {
thp_idx = thp_base + inc;
if (thp_idx < 5 || thp_idx > 0xff)
continue;

- foscl = i2c->sys_freq / (2 * (thp_idx + 1));
+ if (octeon_i2c_is_otx2(to_pci_dev(i2c->dev)))
+ foscl = i2c->sys_freq / (thp_idx + 2);
+ else
+ foscl = i2c->sys_freq /
+ (2 * (thp_idx + 1));
foscl = foscl / (1 << ndiv_idx);
foscl = foscl / (mdiv_idx + 1) / 10;
diff = abs(foscl - i2c->twsi_freq);
+ /* Use it if smaller diff from target */
if (diff < delta_hz) {
delta_hz = diff;
thp = thp_idx;
diff --git a/drivers/i2c/busses/i2c-octeon-core.h b/drivers/i2c/busses/i2c-octeon-core.h
index 9bb9f64fdda0392364638ecbaafe3fab5612baf6..8a0033c94a8a291fb255b0da03858274035c46f4 100644
--- a/drivers/i2c/busses/i2c-octeon-core.h
+++ b/drivers/i2c/busses/i2c-octeon-core.h
@@ -7,6 +7,7 @@
#include <linux/i2c-smbus.h>
#include <linux/io.h>
#include <linux/kernel.h>
+#include <linux/pci.h>

/* Controller command patterns */
#define SW_TWSI_V BIT_ULL(63) /* Valid bit */
@@ -211,6 +212,20 @@ static inline void octeon_i2c_write_int(struct octeon_i2c *i2c, u64 data)
octeon_i2c_writeq_flush(data, i2c->twsi_base + TWSI_INT(i2c));
}

+#define PCI_SUBSYS_DEVID_9XXX 0xB
+/**
+ * octeon_i2c_is_otx2 - check for chip ID
+ * @pdev: PCI dev structure
+ *
+ * Returns TRUE if OcteonTX2, FALSE otherwise.
+ */
+static inline bool octeon_i2c_is_otx2(struct pci_dev *pdev)
+{
+ u32 chip_id = (pdev->subsystem_device >> 12) & 0xF;
+
+ return (chip_id == PCI_SUBSYS_DEVID_9XXX);
+}
+
/* Prototypes */
irqreturn_t octeon_i2c_isr(int irq, void *dev_id);
int octeon_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);
diff --git a/drivers/i2c/busses/i2c-thunderx-pcidrv.c b/drivers/i2c/busses/i2c-thunderx-pcidrv.c
index a77cd86fe75ed7401bc041b27c651b9fedf67285..eecd27f9f1730e522dcccafc9f12ea891a3b59ef 100644
--- a/drivers/i2c/busses/i2c-thunderx-pcidrv.c
+++ b/drivers/i2c/busses/i2c-thunderx-pcidrv.c
@@ -205,6 +205,12 @@ static int thunder_i2c_probe_pci(struct pci_dev *pdev,
if (ret)
goto error;

+ /*
+ * For OcteonTX2 chips, set reference frequency to 100MHz
+ * as refclk_src in TWSI_MODE register defaults to 100MHz.
+ */
+ if (octeon_i2c_is_otx2(pdev))
+ i2c->sys_freq = 100000000;
octeon_i2c_set_clock(i2c);

i2c->adap = thunderx_i2c_ops;
--
2.17.1