[PATCH v2 3/3] b43: Use cordic algorithm from kernel library

[Priit Laes]

Kernel library has a common cordic algorithm which is identical
to internally implementatd one, so use it and drop the duplicate
implementation.

Signed-off-by: Priit Laes <***@plaes.org>

---
v2: Merge the update/removal patches into single patch.
---
drivers/net/wireless/broadcom/b43/Kconfig | 1 +-
drivers/net/wireless/broadcom/b43/phy_common.c | 47 +-------------------
drivers/net/wireless/broadcom/b43/phy_common.h | 9 +----
drivers/net/wireless/broadcom/b43/phy_lp.c | 13 ++---
drivers/net/wireless/broadcom/b43/phy_n.c | 13 ++---
5 files changed, 15 insertions(+), 68 deletions(-)

diff --git a/drivers/net/wireless/broadcom/b43/Kconfig b/drivers/net/wireless/broadcom/b43/Kconfig
index fba8560..3e41457 100644
--- a/drivers/net/wireless/broadcom/b43/Kconfig
+++ b/drivers/net/wireless/broadcom/b43/Kconfig
@@ -4,6 +4,7 @@ config B43
select BCMA if B43_BCMA
select SSB if B43_SSB
select FW_LOADER
+ select CORDIC
---help---
b43 is a driver for the Broadcom 43xx series wireless devices.

diff --git a/drivers/net/wireless/broadcom/b43/phy_common.c b/drivers/net/wireless/broadcom/b43/phy_common.c
index 85f2ca9..98c4fa5 100644
--- a/drivers/net/wireless/broadcom/b43/phy_common.c
+++ b/drivers/net/wireless/broadcom/b43/phy_common.c
@@ -604,50 +604,3 @@ void b43_phy_force_clock(struct b43_wldev *dev, bool force)
#endif
}
}
-
-/* http://bcm-v4.sipsolutions.net/802.11/PHY/Cordic */
-struct b43_c32 b43_cordic(int theta)
-{
- static const u32 arctg[] = {
- 2949120, 1740967, 919879, 466945, 234379, 117304,
- 58666, 29335, 14668, 7334, 3667, 1833,
- 917, 458, 229, 115, 57, 29,
- };
- u8 i;
- s32 tmp;
- s8 signx = 1;
- u32 angle = 0;
- struct b43_c32 ret = { .i = 39797, .q = 0, };
-
- while (theta > (180 << 16))
- theta -= (360 << 16);
- while (theta < -(180 << 16))
- theta += (360 << 16);
-
- if (theta > (90 << 16)) {
- theta -= (180 << 16);
- signx = -1;
- } else if (theta < -(90 << 16)) {
- theta += (180 << 16);
- signx = -1;
- }
-
- for (i = 0; i <= 17; i++) {
- if (theta > angle) {
- tmp = ret.i - (ret.q >> i);
- ret.q += ret.i >> i;
- ret.i = tmp;
- angle += arctg[i];
- } else {
- tmp = ret.i + (ret.q >> i);
- ret.q -= ret.i >> i;
- ret.i = tmp;
- angle -= arctg[i];
- }
- }
-
- ret.i *= signx;
- ret.q *= signx;
-
- return ret;
-}
diff --git a/drivers/net/wireless/broadcom/b43/phy_common.h b/drivers/net/wireless/broadcom/b43/phy_common.h
index 57a1ad8..4213cac 100644
--- a/drivers/net/wireless/broadcom/b43/phy_common.h
+++ b/drivers/net/wireless/broadcom/b43/phy_common.h
@@ -7,13 +7,6 @@

struct b43_wldev;

-/* Complex number using 2 32-bit signed integers */
-struct b43_c32 { s32 i, q; };
-
-#define CORDIC_CONVERT(value) (((value) >= 0) ? \
- ((((value) >> 15) + 1) >> 1) : \
- -((((-(value)) >> 15) + 1) >> 1))
-
/* PHY register routing bits */
#define B43_PHYROUTE 0x0C00 /* PHY register routing bits mask */
#define B43_PHYROUTE_BASE 0x0000 /* Base registers */
@@ -450,6 +443,4 @@ bool b43_is_40mhz(struct b43_wldev *dev);

void b43_phy_force_clock(struct b43_wldev *dev, bool force);

-struct b43_c32 b43_cordic(int theta);
-
#endif /* LINUX_B43_PHY_COMMON_H_ */
diff --git a/drivers/net/wireless/broadcom/b43/phy_lp.c b/drivers/net/wireless/broadcom/b43/phy_lp.c
index 6922cbb..1718e3b 100644
--- a/drivers/net/wireless/broadcom/b43/phy_lp.c
+++ b/drivers/net/wireless/broadcom/b43/phy_lp.c
@@ -23,6 +23,7 @@

*/

+#include <linux/cordic.h>
#include <linux/slab.h>

#include "b43.h"
@@ -1780,9 +1781,9 @@ static void lpphy_start_tx_tone(struct b43_wldev *dev, s32 freq, u16 max)
{
struct b43_phy_lp *lpphy = dev->phy.lp;
u16 buf[64];
- int i, samples = 0, angle = 0;
+ int i, samples = 0, theta = 0;
int rotation = (((36 * freq) / 20) << 16) / 100;
- struct b43_c32 sample;
+ struct cordic_iq sample;

lpphy->tx_tone_freq = freq;

@@ -1798,10 +1799,10 @@ static void lpphy_start_tx_tone(struct b43_wldev *dev, s32 freq, u16 max)
}

for (i = 0; i < samples; i++) {
- sample = b43_cordic(angle);
- angle += rotation;
- buf[i] = CORDIC_CONVERT((sample.i * max) & 0xFF) << 8;
- buf[i] |= CORDIC_CONVERT((sample.q * max) & 0xFF);
+ sample = cordic_calc_iq(theta);
+ theta += rotation;
+ buf[i] = CORDIC_FLOAT((sample.i * max) & 0xFF) << 8;
+ buf[i] |= CORDIC_FLOAT((sample.q * max) & 0xFF);
}

b43_lptab_write_bulk(dev, B43_LPTAB16(5, 0), samples, buf);
diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c
index 44ab080..1f9378a 100644
--- a/drivers/net/wireless/broadcom/b43/phy_n.c
+++ b/drivers/net/wireless/broadcom/b43/phy_n.c
@@ -23,6 +23,7 @@

*/

+#include <linux/cordic.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/types.h>
@@ -1513,7 +1514,7 @@ static void b43_radio_init2055(struct b43_wldev *dev)

/* http://bcm-v4.sipsolutions.net/802.11/PHY/N/LoadSampleTable */
static int b43_nphy_load_samples(struct b43_wldev *dev,
- struct b43_c32 *samples, u16 len) {
+ struct cordic_iq *samples, u16 len) {
struct b43_phy_n *nphy = dev->phy.n;
u16 i;
u32 *data;
@@ -1544,7 +1545,7 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max,
{
int i;
u16 bw, len, rot, angle;
- struct b43_c32 *samples;
+ struct cordic_iq *samples;

bw = b43_is_40mhz(dev) ? 40 : 20;
len = bw << 3;
@@ -1561,7 +1562,7 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max,
len = bw << 1;
}

- samples = kcalloc(len, sizeof(struct b43_c32), GFP_KERNEL);
+ samples = kcalloc(len, sizeof(struct cordic_iq), GFP_KERNEL);
if (!samples) {
b43err(dev->wl, "allocation for samples generation failed\n");
return 0;
@@ -1570,10 +1571,10 @@ static u16 b43_nphy_gen_load_samples(struct b43_wldev *dev, u32 freq, u16 max,
angle = 0;

for (i = 0; i < len; i++) {
- samples[i] = b43_cordic(angle);
+ samples[i] = cordic_calc_iq(angle);
angle += rot;
- samples[i].q = CORDIC_CONVERT(samples[i].q * max);
- samples[i].i = CORDIC_CONVERT(samples[i].i * max);
+ samples[i].q = CORDIC_FLOAT(samples[i].q * max);
+ samples[i].i = CORDIC_FLOAT(samples[i].i * max);
}

i = b43_nphy_load_samples(dev, samples, len);

[Michael Büsch]

On Mon, 5 Nov 2018 21:37:18 +0200

Post by Priit Laes
Kernel library has a common cordic algorithm which is identical
to internally implementatd one, so use it and drop the duplicate
implementation.

This looks nice.
But what is the testing status of this?
Has this been tested on actual b43-LP hardware?

Is the replacement algorithm exactly the same, or are there slight
differences (e.g. in corner cases)?

[Arend van Spriel]

Post by Michael Büsch
On Mon, 5 Nov 2018 21:37:18 +0200

Post by Priit Laes
Kernel library has a common cordic algorithm which is identical
to internally implementatd one, so use it and drop the duplicate
implementation.

This looks nice.
But what is the testing status of this?
Has this been tested on actual b43-LP hardware?
Is the replacement algorithm exactly the same, or are there slight
differences (e.g. in corner cases)?

Hi Michael,

I recall doing a comparison between the algorithms and thought I put
that in the original commit message. However, it is not there. It is not
exactly the same as in b43 so there are difference for certain angles,
most results are the same however. This implementation is slightly more
accurate on the full scale.