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sm501: add support for the SM502 programmable PLL
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SM502 has a programmable PLL which can provide the panel pixel clock instead
of the 288MHz and 336MHz PLLs.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Ville Syrjala <syrjala@sci.fi>
Cc: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Ville Syrjala authored and Linus Torvalds committed Mar 5, 2008
1 parent 245904a commit 3149be5
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Showing 3 changed files with 133 additions and 36 deletions.
163 changes: 128 additions & 35 deletions drivers/mfd/sm501.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@ struct sm501_devdata {
unsigned int pdev_id;
unsigned int irq;
void __iomem *regs;
unsigned int rev;
};

#define MHZ (1000 * 1000)
Expand Down Expand Up @@ -417,46 +418,108 @@ struct sm501_clock {
unsigned long mclk;
int divider;
int shift;
unsigned int m, n, k;
};

/* sm501_calc_clock
*
* Calculates the nearest discrete clock frequency that
* can be achieved with the specified input clock.
* the maximum divisor is 3 or 5
*/

static int sm501_calc_clock(unsigned long freq,
struct sm501_clock *clock,
int max_div,
unsigned long mclk,
long *best_diff)
{
int ret = 0;
int divider;
int shift;
long diff;

/* try dividers 1 and 3 for CRT and for panel,
try divider 5 for panel only.*/

for (divider = 1; divider <= max_div; divider += 2) {
/* try all 8 shift values.*/
for (shift = 0; shift < 8; shift++) {
/* Calculate difference to requested clock */
diff = sm501fb_round_div(mclk, divider << shift) - freq;
if (diff < 0)
diff = -diff;

/* If it is less than the current, use it */
if (diff < *best_diff) {
*best_diff = diff;

clock->mclk = mclk;
clock->divider = divider;
clock->shift = shift;
ret = 1;
}
}
}

return ret;
}

/* sm501_calc_pll
*
* Calculates the nearest discrete clock frequency that can be
* achieved using the programmable PLL.
* the maximum divisor is 3 or 5
*/

static unsigned long sm501_calc_pll(unsigned long freq,
struct sm501_clock *clock,
int max_div)
{
unsigned long mclk;
unsigned int m, n, k;
long best_diff = 999999999;

/*
* The SM502 datasheet doesn't specify the min/max values for M and N.
* N = 1 at least doesn't work in practice.
*/
for (m = 2; m <= 255; m++) {
for (n = 2; n <= 127; n++) {
for (k = 0; k <= 1; k++) {
mclk = (24000000UL * m / n) >> k;

if (sm501_calc_clock(freq, clock, max_div,
mclk, &best_diff)) {
clock->m = m;
clock->n = n;
clock->k = k;
}
}
}
}

/* Return best clock. */
return clock->mclk / (clock->divider << clock->shift);
}

/* sm501_select_clock
*
* selects nearest discrete clock frequency the SM501 can achive
* Calculates the nearest discrete clock frequency that can be
* achieved using the 288MHz and 336MHz PLLs.
* the maximum divisor is 3 or 5
*/

static unsigned long sm501_select_clock(unsigned long freq,
struct sm501_clock *clock,
int max_div)
{
unsigned long mclk;
int divider;
int shift;
long diff;
long best_diff = 999999999;

/* Try 288MHz and 336MHz clocks. */
for (mclk = 288000000; mclk <= 336000000; mclk += 48000000) {
/* try dividers 1 and 3 for CRT and for panel,
try divider 5 for panel only.*/

for (divider = 1; divider <= max_div; divider += 2) {
/* try all 8 shift values.*/
for (shift = 0; shift < 8; shift++) {
/* Calculate difference to requested clock */
diff = sm501fb_round_div(mclk, divider << shift) - freq;
if (diff < 0)
diff = -diff;

/* If it is less than the current, use it */
if (diff < best_diff) {
best_diff = diff;

clock->mclk = mclk;
clock->divider = divider;
clock->shift = shift;
}
}
}
sm501_calc_clock(freq, clock, max_div, mclk, &best_diff);
}

/* Return best clock. */
Expand All @@ -478,6 +541,7 @@ unsigned long sm501_set_clock(struct device *dev,
unsigned long gate = readl(sm->regs + SM501_CURRENT_GATE);
unsigned long clock = readl(sm->regs + SM501_CURRENT_CLOCK);
unsigned char reg;
unsigned int pll_reg = 0;
unsigned long sm501_freq; /* the actual frequency acheived */

struct sm501_clock to;
Expand All @@ -492,14 +556,28 @@ unsigned long sm501_set_clock(struct device *dev,
* requested frequency the value must be multiplied by
* 2. This clock also has an additional pre divisor */

sm501_freq = (sm501_select_clock(2 * req_freq, &to, 5) / 2);
reg=to.shift & 0x07;/* bottom 3 bits are shift */
if (to.divider == 3)
reg |= 0x08; /* /3 divider required */
else if (to.divider == 5)
reg |= 0x10; /* /5 divider required */
if (to.mclk != 288000000)
reg |= 0x20; /* which mclk pll is source */
if (sm->rev >= 0xC0) {
/* SM502 -> use the programmable PLL */
sm501_freq = (sm501_calc_pll(2 * req_freq,
&to, 5) / 2);
reg = to.shift & 0x07;/* bottom 3 bits are shift */
if (to.divider == 3)
reg |= 0x08; /* /3 divider required */
else if (to.divider == 5)
reg |= 0x10; /* /5 divider required */
reg |= 0x40; /* select the programmable PLL */
pll_reg = 0x20000 | (to.k << 15) | (to.n << 8) | to.m;
} else {
sm501_freq = (sm501_select_clock(2 * req_freq,
&to, 5) / 2);
reg = to.shift & 0x07;/* bottom 3 bits are shift */
if (to.divider == 3)
reg |= 0x08; /* /3 divider required */
else if (to.divider == 5)
reg |= 0x10; /* /5 divider required */
if (to.mclk != 288000000)
reg |= 0x20; /* which mclk pll is source */
}
break;

case SM501_CLOCK_V2XCLK:
Expand Down Expand Up @@ -560,6 +638,10 @@ unsigned long sm501_set_clock(struct device *dev,
}

writel(mode, sm->regs + SM501_POWER_MODE_CONTROL);

if (pll_reg)
writel(pll_reg, sm->regs + SM501_PROGRAMMABLE_PLL_CONTROL);

sm501_sync_regs(sm);

dev_info(sm->dev, "gate %08lx, clock %08lx, mode %08lx\n",
Expand All @@ -580,15 +662,24 @@ EXPORT_SYMBOL_GPL(sm501_set_clock);
* finds the closest available frequency for a given clock
*/

unsigned long sm501_find_clock(int clksrc,
unsigned long sm501_find_clock(struct device *dev,
int clksrc,
unsigned long req_freq)
{
struct sm501_devdata *sm = dev_get_drvdata(dev);
unsigned long sm501_freq; /* the frequency achiveable by the 501 */
struct sm501_clock to;

switch (clksrc) {
case SM501_CLOCK_P2XCLK:
sm501_freq = (sm501_select_clock(2 * req_freq, &to, 5) / 2);
if (sm->rev >= 0xC0) {
/* SM502 -> use the programmable PLL */
sm501_freq = (sm501_calc_pll(2 * req_freq,
&to, 5) / 2);
} else {
sm501_freq = (sm501_select_clock(2 * req_freq,
&to, 5) / 2);
}
break;

case SM501_CLOCK_V2XCLK:
Expand Down Expand Up @@ -895,6 +986,8 @@ static int sm501_init_dev(struct sm501_devdata *sm)
dev_info(sm->dev, "SM501 At %p: Version %08lx, %ld Mb, IRQ %d\n",
sm->regs, devid, (unsigned long)mem_avail >> 20, sm->irq);

sm->rev = devid & SM501_DEVICEID_REVMASK;

sm501_dump_gate(sm);

ret = device_create_file(sm->dev, &dev_attr_dbg_regs);
Expand Down
3 changes: 3 additions & 0 deletions include/linux/sm501-regs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -129,11 +129,14 @@

#define SM501_DEVICEID_SM501 (0x05010000)
#define SM501_DEVICEID_IDMASK (0xffff0000)
#define SM501_DEVICEID_REVMASK (0x000000ff)

#define SM501_PLLCLOCK_COUNT (0x000064)
#define SM501_MISC_TIMING (0x000068)
#define SM501_CURRENT_SDRAM_CLOCK (0x00006C)

#define SM501_PROGRAMMABLE_PLL_CONTROL (0x000074)

/* GPIO base */
#define SM501_GPIO (0x010000)
#define SM501_GPIO_DATA_LOW (0x00)
Expand Down
3 changes: 2 additions & 1 deletion include/linux/sm501.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,8 @@ extern int sm501_unit_power(struct device *dev,
extern unsigned long sm501_set_clock(struct device *dev,
int clksrc, unsigned long freq);

extern unsigned long sm501_find_clock(int clksrc, unsigned long req_freq);
extern unsigned long sm501_find_clock(struct device *dev,
int clksrc, unsigned long req_freq);

/* sm501_misc_control
*
Expand Down

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