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ARM: at91/tc/clocksource: Add 32 bit variant to Timer Counter
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Some SoC have a 32 bit variant of Timer Counter Blocks. We do not
need the chaining of two 16 bit counters anymore for them.

The SoC nature is deduced from the device tree "compatible" string.
For non-device-tree configurations, backward compatibility is maintained
by using the default 16 bit counter configuration.

This patch addresses both the atmel_tclib and its user: tcb_clksrc
clocksource.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
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Nicolas Ferre committed Mar 1, 2012
1 parent 3a61a5d commit 8e315a7
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Showing 3 changed files with 92 additions and 28 deletions.
90 changes: 62 additions & 28 deletions drivers/clocksource/tcb_clksrc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,8 @@
* - Two channels combine to create a free-running 32 bit counter
* with a base rate of 5+ MHz, packaged as a clocksource (with
* resolution better than 200 nsec).
* - Some chips support 32 bit counter. A single channel is used for
* this 32 bit free-running counter. the second channel is not used.
*
* - The third channel may be used to provide a 16-bit clockevent
* source, used in either periodic or oneshot mode. This runs
Expand Down Expand Up @@ -54,6 +56,11 @@ static cycle_t tc_get_cycles(struct clocksource *cs)
return (upper << 16) | lower;
}

static cycle_t tc_get_cycles32(struct clocksource *cs)
{
return __raw_readl(tcaddr + ATMEL_TC_REG(0, CV));
}

static struct clocksource clksrc = {
.name = "tcb_clksrc",
.rating = 200,
Expand Down Expand Up @@ -209,6 +216,48 @@ static void __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)

#endif

static void __init tcb_setup_dual_chan(struct atmel_tc *tc, int mck_divisor_idx)
{
/* channel 0: waveform mode, input mclk/8, clock TIOA0 on overflow */
__raw_writel(mck_divisor_idx /* likely divide-by-8 */
| ATMEL_TC_WAVE
| ATMEL_TC_WAVESEL_UP /* free-run */
| ATMEL_TC_ACPA_SET /* TIOA0 rises at 0 */
| ATMEL_TC_ACPC_CLEAR, /* (duty cycle 50%) */
tcaddr + ATMEL_TC_REG(0, CMR));
__raw_writel(0x0000, tcaddr + ATMEL_TC_REG(0, RA));
__raw_writel(0x8000, tcaddr + ATMEL_TC_REG(0, RC));
__raw_writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR)); /* no irqs */
__raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR));

/* channel 1: waveform mode, input TIOA0 */
__raw_writel(ATMEL_TC_XC1 /* input: TIOA0 */
| ATMEL_TC_WAVE
| ATMEL_TC_WAVESEL_UP, /* free-run */
tcaddr + ATMEL_TC_REG(1, CMR));
__raw_writel(0xff, tcaddr + ATMEL_TC_REG(1, IDR)); /* no irqs */
__raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(1, CCR));

/* chain channel 0 to channel 1*/
__raw_writel(ATMEL_TC_TC1XC1S_TIOA0, tcaddr + ATMEL_TC_BMR);
/* then reset all the timers */
__raw_writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR);
}

static void __init tcb_setup_single_chan(struct atmel_tc *tc, int mck_divisor_idx)
{
/* channel 0: waveform mode, input mclk/8 */
__raw_writel(mck_divisor_idx /* likely divide-by-8 */
| ATMEL_TC_WAVE
| ATMEL_TC_WAVESEL_UP, /* free-run */
tcaddr + ATMEL_TC_REG(0, CMR));
__raw_writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR)); /* no irqs */
__raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR));

/* then reset all the timers */
__raw_writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR);
}

static int __init tcb_clksrc_init(void)
{
static char bootinfo[] __initdata
Expand Down Expand Up @@ -260,34 +309,19 @@ static int __init tcb_clksrc_init(void)
divided_rate / 1000000,
((divided_rate + 500000) % 1000000) / 1000);

/* tclib will give us three clocks no matter what the
* underlying platform supports.
*/
clk_enable(tc->clk[1]);

/* channel 0: waveform mode, input mclk/8, clock TIOA0 on overflow */
__raw_writel(best_divisor_idx /* likely divide-by-8 */
| ATMEL_TC_WAVE
| ATMEL_TC_WAVESEL_UP /* free-run */
| ATMEL_TC_ACPA_SET /* TIOA0 rises at 0 */
| ATMEL_TC_ACPC_CLEAR, /* (duty cycle 50%) */
tcaddr + ATMEL_TC_REG(0, CMR));
__raw_writel(0x0000, tcaddr + ATMEL_TC_REG(0, RA));
__raw_writel(0x8000, tcaddr + ATMEL_TC_REG(0, RC));
__raw_writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR)); /* no irqs */
__raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR));

/* channel 1: waveform mode, input TIOA0 */
__raw_writel(ATMEL_TC_XC1 /* input: TIOA0 */
| ATMEL_TC_WAVE
| ATMEL_TC_WAVESEL_UP, /* free-run */
tcaddr + ATMEL_TC_REG(1, CMR));
__raw_writel(0xff, tcaddr + ATMEL_TC_REG(1, IDR)); /* no irqs */
__raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(1, CCR));

/* chain channel 0 to channel 1, then reset all the timers */
__raw_writel(ATMEL_TC_TC1XC1S_TIOA0, tcaddr + ATMEL_TC_BMR);
__raw_writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR);
if (tc->tcb_config && tc->tcb_config->counter_width == 32) {
/* use apropriate function to read 32 bit counter */
clksrc.read = tc_get_cycles32;
/* setup ony channel 0 */
tcb_setup_single_chan(tc, best_divisor_idx);
} else {
/* tclib will give us three clocks no matter what the
* underlying platform supports.
*/
clk_enable(tc->clk[1]);
/* setup both channel 0 & 1 */
tcb_setup_dual_chan(tc, best_divisor_idx);
}

/* and away we go! */
clocksource_register_hz(&clksrc, divided_rate);
Expand Down
20 changes: 20 additions & 0 deletions drivers/misc/atmel_tclib.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -114,9 +114,21 @@ void atmel_tc_free(struct atmel_tc *tc)
EXPORT_SYMBOL_GPL(atmel_tc_free);

#if defined(CONFIG_OF)
static struct atmel_tcb_config tcb_rm9200_config = {
.counter_width = 16,
};

static struct atmel_tcb_config tcb_sam9x5_config = {
.counter_width = 32,
};

static const struct of_device_id atmel_tcb_dt_ids[] = {
{
.compatible = "atmel,at91rm9200-tcb",
.data = &tcb_rm9200_config,
}, {
.compatible = "atmel,at91sam9x5-tcb",
.data = &tcb_sam9x5_config,
}, {
/* sentinel */
}
Expand Down Expand Up @@ -150,6 +162,14 @@ static int __init tc_probe(struct platform_device *pdev)
return -EINVAL;
}

/* Now take SoC information if available */
if (pdev->dev.of_node) {
const struct of_device_id *match;
match = of_match_node(atmel_tcb_dt_ids, pdev->dev.of_node);
if (match)
tc->tcb_config = match->data;
}

tc->clk[0] = clk;
tc->clk[1] = clk_get(&pdev->dev, "t1_clk");
if (IS_ERR(tc->clk[1]))
Expand Down
10 changes: 10 additions & 0 deletions include/linux/atmel_tc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -33,11 +33,20 @@

struct clk;

/**
* struct atmel_tcb_config - SoC data for a Timer/Counter Block
* @counter_width: size in bits of a timer counter register
*/
struct atmel_tcb_config {
size_t counter_width;
};

/**
* struct atmel_tc - information about a Timer/Counter Block
* @pdev: physical device
* @iomem: resource associated with the I/O register
* @regs: mapping through which the I/O registers can be accessed
* @tcb_config: configuration data from SoC
* @irq: irq for each of the three channels
* @clk: internal clock source for each of the three channels
* @node: list node, for tclib internal use
Expand All @@ -54,6 +63,7 @@ struct atmel_tc {
struct platform_device *pdev;
struct resource *iomem;
void __iomem *regs;
struct atmel_tcb_config *tcb_config;
int irq[3];
struct clk *clk[3];
struct list_head node;
Expand Down

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