#define ORION_SPI_DATA_OUT_REG 0x08
#define ORION_SPI_DATA_IN_REG 0x0c
#define ORION_SPI_INT_CAUSE_REG 0x10
+#define ORION_SPI_TIMING_PARAMS_REG 0x18
+
+#define ORION_SPI_TMISO_SAMPLE_MASK (0x3 << 6)
+#define ORION_SPI_TMISO_SAMPLE_1 (1 << 6)
+#define ORION_SPI_TMISO_SAMPLE_2 (2 << 6)
#define ORION_SPI_MODE_CPOL (1 << 11)
#define ORION_SPI_MODE_CPHA (1 << 12)
unsigned int min_divisor;
unsigned int max_divisor;
u32 prescale_mask;
+ bool is_errata_50mhz_ac;
};
struct orion_spi {
tclk_hz = clk_get_rate(orion_spi->clk);
if (devdata->typ == ARMADA_SPI) {
- unsigned int clk, spr, sppr, sppr2, err;
- unsigned int best_spr, best_sppr, best_err;
-
- best_err = speed;
- best_spr = 0;
- best_sppr = 0;
-
- /* Iterate over the valid range looking for best fit */
- for (sppr = 0; sppr < 8; sppr++) {
- sppr2 = 0x1 << sppr;
-
- spr = tclk_hz / sppr2;
- spr = DIV_ROUND_UP(spr, speed);
- if ((spr == 0) || (spr > 15))
- continue;
-
- clk = tclk_hz / (spr * sppr2);
- err = speed - clk;
-
- if (err < best_err) {
- best_spr = spr;
- best_sppr = sppr;
- best_err = err;
- }
- }
+ /*
+ * Given the core_clk (tclk_hz) and the target rate (speed) we
+ * determine the best values for SPR (in [0 .. 15]) and SPPR (in
+ * [0..7]) such that
+ *
+ * core_clk / (SPR * 2 ** SPPR)
+ *
+ * is as big as possible but not bigger than speed.
+ */
- if ((best_sppr == 0) && (best_spr == 0))
- return -EINVAL;
+ /* best integer divider: */
+ unsigned divider = DIV_ROUND_UP(tclk_hz, speed);
+ unsigned spr, sppr;
+
+ if (divider < 16) {
+ /* This is the easy case, divider is less than 16 */
+ spr = divider;
+ sppr = 0;
+
+ } else {
+ unsigned two_pow_sppr;
+ /*
+ * Find the highest bit set in divider. This and the
+ * three next bits define SPR (apart from rounding).
+ * SPPR is then the number of zero bits that must be
+ * appended:
+ */
+ sppr = fls(divider) - 4;
+
+ /*
+ * As SPR only has 4 bits, we have to round divider up
+ * to the next multiple of 2 ** sppr.
+ */
+ two_pow_sppr = 1 << sppr;
+ divider = (divider + two_pow_sppr - 1) & -two_pow_sppr;
+
+ /*
+ * recalculate sppr as rounding up divider might have
+ * increased it enough to change the position of the
+ * highest set bit. In this case the bit that now
+ * doesn't make it into SPR is 0, so there is no need to
+ * round again.
+ */
+ sppr = fls(divider) - 4;
+ spr = divider >> sppr;
+
+ /*
+ * Now do range checking. SPR is constructed to have a
+ * width of 4 bits, so this is fine for sure. So we
+ * still need to check for sppr to fit into 3 bits:
+ */
+ if (sppr > 7)
+ return -EINVAL;
+ }
- prescale = ((best_sppr & 0x6) << 5) |
- ((best_sppr & 0x1) << 4) | best_spr;
+ prescale = ((sppr & 0x6) << 5) | ((sppr & 0x1) << 4) | spr;
} else {
/*
* the supported rates are: 4,6,8...30
writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
}
+static void
+orion_spi_50mhz_ac_timing_erratum(struct spi_device *spi, unsigned int speed)
+{
+ u32 reg;
+ struct orion_spi *orion_spi;
+
+ orion_spi = spi_master_get_devdata(spi->master);
+
+ /*
+ * Erratum description: (Erratum NO. FE-9144572) The device
+ * SPI interface supports frequencies of up to 50 MHz.
+ * However, due to this erratum, when the device core clock is
+ * 250 MHz and the SPI interfaces is configured for 50MHz SPI
+ * clock and CPOL=CPHA=1 there might occur data corruption on
+ * reads from the SPI device.
+ * Erratum Workaround:
+ * Work in one of the following configurations:
+ * 1. Set CPOL=CPHA=0 in "SPI Interface Configuration
+ * Register".
+ * 2. Set TMISO_SAMPLE value to 0x2 in "SPI Timing Parameters 1
+ * Register" before setting the interface.
+ */
+ reg = readl(spi_reg(orion_spi, ORION_SPI_TIMING_PARAMS_REG));
+ reg &= ~ORION_SPI_TMISO_SAMPLE_MASK;
+
+ if (clk_get_rate(orion_spi->clk) == 250000000 &&
+ speed == 50000000 && spi->mode & SPI_CPOL &&
+ spi->mode & SPI_CPHA)
+ reg |= ORION_SPI_TMISO_SAMPLE_2;
+ else
+ reg |= ORION_SPI_TMISO_SAMPLE_1; /* This is the default value */
+
+ writel(reg, spi_reg(orion_spi, ORION_SPI_TIMING_PARAMS_REG));
+}
+
/*
* called only when no transfer is active on the bus
*/
orion_spi_mode_set(spi);
+ if (orion_spi->devdata->is_errata_50mhz_ac)
+ orion_spi_50mhz_ac_timing_erratum(spi, speed);
+
rc = orion_spi_baudrate_set(spi, speed);
if (rc)
return rc;
.prescale_mask = ORION_SPI_CLK_PRESCALE_MASK,
};
-static const struct orion_spi_dev armada_spi_dev_data = {
+static const struct orion_spi_dev armada_370_spi_dev_data = {
.typ = ARMADA_SPI,
.min_divisor = 4,
.max_divisor = 1920,
.prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
};
+static const struct orion_spi_dev armada_xp_spi_dev_data = {
+ .typ = ARMADA_SPI,
+ .max_hz = 50000000,
+ .max_divisor = 1920,
+ .prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
+};
+
+static const struct orion_spi_dev armada_375_spi_dev_data = {
+ .typ = ARMADA_SPI,
+ .min_divisor = 15,
+ .max_divisor = 1920,
+ .prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
+};
+
+static const struct orion_spi_dev armada_380_spi_dev_data = {
+ .typ = ARMADA_SPI,
+ .max_hz = 50000000,
+ .max_divisor = 1920,
+ .prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
+ .is_errata_50mhz_ac = true,
+};
+
static const struct of_device_id orion_spi_of_match_table[] = {
- { .compatible = "marvell,orion-spi", .data = &orion_spi_dev_data, },
- { .compatible = "marvell,armada-370-spi", .data = &armada_spi_dev_data, },
+ {
+ .compatible = "marvell,orion-spi",
+ .data = &orion_spi_dev_data,
+ },
+ {
+ .compatible = "marvell,armada-370-spi",
+ .data = &armada_370_spi_dev_data,
+ },
+ {
+ .compatible = "marvell,armada-375-spi",
+ .data = &armada_375_spi_dev_data,
+ },
+ {
+ .compatible = "marvell,armada-380-spi",
+ .data = &armada_380_spi_dev_data,
+ },
+ {
+ .compatible = "marvell,armada-390-spi",
+ .data = &armada_xp_spi_dev_data,
+ },
+ {
+ .compatible = "marvell,armada-xp-spi",
+ .data = &armada_xp_spi_dev_data,
+ },
+
{}
};
MODULE_DEVICE_TABLE(of, orion_spi_of_match_table);
"marvell,armada-370-spi"))
master->max_speed_hz = min(devdata->max_hz,
DIV_ROUND_UP(tclk_hz, devdata->min_divisor));
- else
+ else if (devdata->min_divisor)
master->max_speed_hz =
DIV_ROUND_UP(tclk_hz, devdata->min_divisor);
+ else
+ master->max_speed_hz = devdata->max_hz;
master->min_speed_hz = DIV_ROUND_UP(tclk_hz, devdata->max_divisor);
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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